Polycarbonate block copolymers

ABSTRACT

The disclosure pertains to amphiphilic block copolymers comprising an aliphatic polycarbonate chain coupled to a hydrophilic polymer. Such amphiphilic polymers may have the formula A-L-B, where A- is a polycarbonate or polyethercarbonate chain having from about 3 to about 500 repeating units, L is a linker moiety and -B is a hydrophilic oligomer having from about 4 to about 200 repeating units. Provided copolymers are useful as surfactants capable of emulsifying aqueous solutions and supercritical carbon dioxide. Provided copolymers also have utility as additives for use in enhanced oil recovery methods.

PRIORITY CLAIM

This application is a continuation of U.S. Pat. No. 8,785,591, which isa continuation of a U.S. Pat. No. 8,580,911, which is U.S. nationalphase application under 35 U.S.C. §371 of PCT application no.PCT/US09/62871, filed Oct. 30, 2009, which claims priority to U.S.Provisional Patent Application Ser. No. 61/110,567, filed Nov. 1, 2008.The entire contents of this priority application is incorporated hereinby reference.

BACKGROUND

Carbon dioxide is of great interest as a solvent in chemical processingbecause it is non-flammable, relatively non-toxic, and naturallyabundant. These “green” properties have prompted the development of ahost of new applications for CO₂, some of which were made possible bythe discovery of functional groups that enable miscibility of variousmoieties with CO₂ at moderate pressures. Development of CO₂ surfactants,for example, allows for processes such as emulsion polymerization or drycleaning with CO₂.

CO₂ has been extensively employed to recover oil from undergroundformations, as it is inexpensive, non-flammable, relatively non-toxicand remediation is not required. In enhanced oil recovery (EOR), aflooding agent is pumped into the oil-bearing formation to move thepetroleum to exit wells (see for example U.S. Pat. Nos. 4,480,696,4,921,635 and 5,566,470). Water is most often used as the floodingagent, yet intimate contact between petroleum and water createscross-contamination that mandates remediation of large volumes oforganic-contaminated water. Indeed, a life cycle analysis of polystyreneperformed during the 1980's suggested that the extraction of petroleumfrom the ground produces more liquid waste than any other process stepover the entire cradle-to-grave lifespan of the material. Carbon dioxidewould be a more sustainable flooding agent than water, but the viscosityof CO₂ is too low to efficiently recover petroleum from the formation.Rather than sweep the oil before it, carbon dioxide “fingers” its waythrough the petroleum and hence leaves most of the oil behind.

Researchers in the petroleum engineering field have tried for decades todesign additives that can raise the viscosity of carbon dioxide (at lowconcentration) to levels that would render CO₂-flooding more practical,but success has been elusive. Additives have been synthesized thatenhanced the viscosity of simple hydrocarbons, yet which were notsoluble in CO₂ without the use of impractically high fractions ofco-solvent. Other additives have been identified that were CO₂-solublebut which did produce any changes in the viscosity of CO₂.

Polymer-based surfactants have also been developed for use in increasingthe viscosity of CO₂ and/or CO₂ solubility (WO 00/35998 and U.S. Pat.No. 6,686,438). However, these materials have not found much practicalutility due to issues with their relative solubility in CO₂ and water,specifically in their tendency to be hydrophilic but not veryCO₂-philic.

Improvement in the efficiency of CO₂-flooding will promote the use ofCO₂ over water in EOR and thus reduce the volume of liquid wasteproduced during petroleum extraction. Use of CO₂ in EOR also results inits sequestration in rock formations, potentially an important part ofan overall CO₂ sequestration strategy. Thus, what is at first glancesimply a technical problem in petroleum engineering has significantenvironmental ramifications as well. This discussion highlights the needfor compositions that increase the viscosity of fluids comprisingsupercritical CO₂ and water.

SUMMARY OF THE INVENTION

The present disclosure provides, among other things, amphiphilicpolymers having the formula A-L-B, wherein each of A, L, and B is asdefined and described in classes and subclasses herein.

In some embodiments, the present disclosure provides amphiphilicpolymers having the formula A-B-A, wherein each of A and B is as definedand described in classes and subclasses herein.

In some embodiments, the present disclosure provides methods to makepolymers of formula A-L-B or A-B-A.

In certain embodiments, provided copolymers are surfactants capable ofcompatibilizing aqueous solutions and supercritical carbon dioxide. Incertain embodiments, provided copolymers are viscosity modifiers capableof increasing the viscosity of supercritical carbon dioxide mixtures. Incertain embodiments, provided copolymers have utility as additives foruse in enhanced oil recovery methods. In certain embodiments, providedcopolymers are useful for forming polymersomes.

DEFINITIONS

Definitions of specific functional groups and chemical terms aredescribed in more detail below. For purposes of this invention, thechemical elements are identified in accordance with the Periodic Tableof the Elements, CAS version, Handbook of Chemistry and Physics, 75^(th)Ed., inside cover, and specific functional groups are generally definedas described therein. Additionally, general principles of organicchemistry, as well as specific functional moieties and reactivity, aredescribed in Organic Chemistry, Thomas Sorrell, University ScienceBooks, Sausalito, 1999; Smith and March March's Advanced OrganicChemistry, 5^(th) Edition, John Wiley & Sons, Inc., New York, 2001;Larock, Comprehensive Organic Transformations, VCH Publishers, Inc., NewYork, 1989; Carruthers, Some Modern Methods of Organic Synthesis, 3^(rd)Edition, Cambridge University Press, Cambridge, 1987; the entirecontents of each of which are incorporated herein by reference.

Certain compounds of the present invention can comprise one or moreasymmetric centers, and thus can exist in various stereoisomeric forms,e.g., enantiomers and/or diastereomers. Thus, inventive compounds andcompositions thereof may be in the form of an individual enantiomer,diastereomer or geometric isomer, or may be in the form of a mixture ofstereoisomers. In certain embodiments, the compounds of the inventionare enantiopure compounds. In certain embodiments, mixtures ofenantiomers or diastereomers are provided.

Furthermore, certain compounds, as described herein may have one or moredouble bonds that can exist as either the Z or E isomer, unlessotherwise indicated. The invention additionally encompasses thecompounds as individual isomers substantially free of other isomers andalternatively, as mixtures of various isomers, e.g., racemic mixtures ofenantiomers.

As used herein, the term “isomers” includes any and all geometricisomers and stereoisomers. For example, “isomers” include cis- andtrans-isomers, E- and Z-isomers, R- and S-enantiomers, diastereomers,(D)-isomers, (L)-isomers, racemic mixtures thereof, and other mixturesthereof, as falling within the scope of the invention. For instance, anstereoisomer may, in some embodiments, be provided substantially free ofone or more corresponding stereoisomers, and may also be referred to as“stereochemically enriched.”

Where a particular enantiomer is preferred, it may, in some embodimentsbe provided substantially free of the opposite enantiomer, and may alsobe referred to as “optically enriched.” “Optically enriched,” as usedherein, means that the compound is made up of a significantly greaterproportion of one enantiomer. In certain embodiments the compound ismade up of at least about 90% by weight of a preferred enantiomer. Inother embodiments the compound is made up of at least about 95%, 98%, or99% by weight of a preferred enantiomer. Preferred enantiomers may beisolated from racemic mixtures by any method known to those skilled inthe art, including chiral high pressure liquid chromatography (HPLC) andthe formation and crystallization of chiral salts or prepared byasymmetric syntheses. See, for example, Jacques, et al., Enantiomers,Racemates and Resolutions (Wiley Interscience, New York, 1981); Wilen,S. H., et al., Tetrahedron 33:2725 (1977); Eliel, E. L. Stereochemistryof Carbon Compounds (McGraw-Hill, NY, 1962); Wilen, S. H. Tables ofResolving Agents and Optical Resolutions p. 268 (E. L. Eliel, Ed., Univ.of Notre Dame Press, Notre Dame, Ind. 1972).

The terms “halo” and “halogen” as used herein refer to an atom selectedfrom fluorine (fluoro, —F), chlorine (chloro, —Cl), bromine (bromo,—Br), and iodine (iodo, —I).

The term “aliphatic” or “aliphatic group”, as used herein, denotes ahydrocarbon moiety that may be straight-chain (i.e., unbranched),branched, or cyclic (including fused, bridging, and spiro-fusedpolycyclic) and may be completely saturated or may contain one or moreunits of unsaturation, but which is not aromatic. Unless otherwisespecified, aliphatic groups contain 1-30 carbon atoms. In certainembodiments, aliphatic groups contain 1-12 carbon atoms. In certainembodiments, aliphatic groups contain 1-8 carbon atoms. In certainembodiments, aliphatic groups contain 1-6 carbon atoms. In someembodiments, aliphatic groups contain 1-5 carbon atoms. In someembodiments, aliphatic groups contain 1-4 carbon atoms. In someembodiments, aliphatic groups contain 1-3 carbon atoms. In someembodiments, aliphatic groups contain 1-2 carbon atoms. Suitablealiphatic groups include, but are not limited to, linear or branched,alkyl, alkenyl, and alkynyl groups, and hybrids thereof such as(cycloalkyl)alkyl, (cycloalkenyl)alkyl or (cycloalkyl)alkenyl.

The term “unsaturated”, as used herein, means that a moiety has one ormore double or triple bonds.

The terms “cycloaliphatic”, “carbocycle”, or “carbocyclic”, used aloneor as part of a larger moiety, refer to a saturated or partiallyunsaturated cyclic aliphatic monocyclic or bicyclic ring systems, asdescribed herein, having from 3 to 12 members, wherein the aliphaticring system is optionally substituted as defined above and describedherein. Cycloaliphatic groups include, without limitation, cyclopropyl,cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl,cycloheptyl, cycloheptenyl, cyclooctyl, cyclooctenyl, andcyclooctadienyl. In some embodiments, the cycloalkyl has 3-6 carbons.The terms “cycloaliphatic”, “carbocycle” or “carbocyclic” also includealiphatic rings that are fused to one or more aromatic or nonaromaticrings, such as decahydronaphthyl or tetrahydronaphthyl, where theradical or point of attachment is on the aliphatic ring. In certainembodiments, the term “3- to 8-membered carbocycle” refers to a 3- to8-membered saturated or partially unsaturated monocyclic carbocyclicring. In certain embodiments, the terms “3- to 14-membered carbocycle”and “C₃₋₁₄ carbocycle” refer to a 3- to 8-membered saturated orpartially unsaturated monocyclic carbocyclic ring, or a 7- to14-membered saturated or partially unsaturated polycyclic carbocyclicring. In certain embodiments, the term “C₃₋₂₀ carbocycle” refers to a 3-to 8-membered saturated or partially unsaturated monocyclic carbocyclicring, or a 7- to 20-membered saturated or partially unsaturatedpolycyclic carbocyclic ring.

The term “alkyl,” as used herein, refers to saturated, straight- orbranched-chain hydrocarbon radicals derived from an aliphatic moietycontaining between one and six carbon atoms by removal of a singlehydrogen atom. Unless otherwise specified, alkyl groups contain 1-12carbon atoms. In certain embodiments, alkyl groups contain 1-8 carbonatoms. In certain embodiments, alkyl groups contain 1-6 carbon atoms. Insome embodiments, alkyl groups contain 1-5 carbon atoms. In someembodiments, alkyl groups contain 1-4 carbon atoms. In certainembodiments, alkyl groups contain 1-3 carbon atoms. In some embodiments,alkyl groups contain 1-2 carbon atoms. Examples of alkyl radicalsinclude, but are not limited to, methyl, ethyl, n-propyl, isopropyl,n-butyl, iso-butyl, sec-butyl, sec-pentyl, iso-pentyl, tert-butyl,n-pentyl, neopentyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, n-decyl,n-undecyl, dodecyl, and the like.

The term “alkenyl,” as used herein, denotes a monovalent group derivedfrom a straight- or branched-chain aliphatic moiety having at least onecarbon-carbon double bond by the removal of a single hydrogen atom.Unless otherwise specified, alkenyl groups contain 2-12 carbon atoms. Incertain embodiments, alkenyl groups contain 2-8 carbon atoms. In certainembodiments, alkenyl groups contain 2-6 carbon atoms. In someembodiments, alkenyl groups contain 2-5 carbon atoms. In someembodiments, alkenyl groups contain 2-4 carbon atoms. In someembodiments, alkenyl groups contain 2-3 carbon atoms. In someembodiments, alkenyl groups contain 2 carbon atoms. Alkenyl groupsinclude, for example, ethenyl, propenyl, butenyl, 1-methyl-2-buten-1-yl,and the like.

The term “alkynyl,” as used herein, refers to a monovalent group derivedfrom a straight- or branched-chain aliphatic moiety having at least onecarbon-carbon triple bond by the removal of a single hydrogen atom.Unless otherwise specified, alkynyl groups contain 2-12 carbon atoms. Incertain embodiments, alkynyl groups contain 2-8 carbon atoms. In certainembodiments, alkynyl groups contain 2-6 carbon atoms. In someembodiments, alkynyl groups contain 2-5 carbon atoms. In someembodiments, alkynyl groups contain 2-4 carbon atoms. In someembodiments, alkynyl groups contain 2-3 carbon atoms. In someembodiments, alkynyl groups contain 2 carbon atoms. Representativealkynyl groups include, but are not limited to, ethynyl, 2-propynyl(propargyl), 1-propynyl, and the like.

The term “aryl” used alone or as part of a larger moiety as in“aralkyl”, “aralkoxy”, or “aryloxyalkyl”, refers to monocyclic andpolycyclic ring systems having a total of five to 20 ring members,wherein at least one ring in the system is aromatic and wherein eachring in the system contains three to twelve ring members. The term“aryl” may be used interchangeably with the term “aryl ring”. In certainembodiments of the present invention, “aryl” refers to an aromatic ringsystem which includes, but is not limited to, phenyl, biphenyl,naphthyl, anthracyl and the like, which may bear one or moresubstituents. Also included within the scope of the term “aryl”, as itis used herein, is a group in which an aromatic ring is fused to one ormore additional rings, such as benzofuranyl, indanyl, phthalimidyl,naphthimidyl, phenantriidinyl, or tetrahydronaphthyl, and the like. Incertain embodiments, the terms “6- to 10-membered aryl” and “C₆₋₁₀ aryl”refer to a phenyl or an 8- to 10-membered polycyclic aryl ring. Incertain embodiments, the term “6- to 14-membered aryl” refers to aphenyl or an 8- to 14-membered polycyclic aryl ring.

The terms “heteroaryl” and “heteroar-”, used alone or as part of alarger moiety, e.g., “heteroaralkyl”, or “heteroaralkoxy”, refer togroups having 5 to 14 ring atoms, preferably 5, 6, or 9 ring atoms;having 6, 10, or 14 π electrons shared in a cyclic array; and having, inaddition to carbon atoms, from one to five heteroatoms. The term“heteroatom” refers to nitrogen, oxygen, or sulfur, and includes anyoxidized form of nitrogen or sulfur, and any quaternized form of a basicnitrogen. Heteroaryl groups include, without limitation, thienyl,furanyl, pyrrolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl,oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl,thiadiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolizinyl,purinyl, naphthyridinyl, benzofuranyl and pteridinyl. The terms“heteroaryl” and “heteroar-”, as used herein, also include groups inwhich a heteroaromatic ring is fused to one or more aryl,cycloaliphatic, or heterocyclyl rings, where the radical or point ofattachment is on the heteroaromatic ring. Nonlimiting examples includeindolyl, isoindolyl, benzothienyl, benzofuranyl, dibenzofuranyl,indazolyl, benzimidazolyl, benzthiazolyl, quinolyl, isoquinolyl,cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, 4H-quinolizinyl,carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl,tetrahydroquinolinyl, tetrahydroisoquinolinyl, andpyrido[2,3-b]-1,4-oxazin-3(4H)-one. A heteroaryl group may be mono- orbicyclic. The term “heteroaryl” may be used interchangeably with theterms “heteroaryl ring”, “heteroaryl group”, or “heteroaromatic”, any ofwhich terms include rings that are optionally substituted. The term“heteroaralkyl” refers to an alkyl group substituted by a heteroaryl,wherein the alkyl and heteroaryl portions independently are optionallysubstituted. In certain embodiments, the term “5- to 10-memberedheteroaryl” refers to a 5- to 6-membered heteroaryl ring having 1 to 3heteroatoms independently selected from nitrogen, oxygen, or sulfur, oran 8- to 10-membered bicyclic heteroaryl ring having 1 to 4 heteroatomsindependently selected from nitrogen, oxygen, or sulfur. In certainembodiments, the term “5- to 14-membered heteroaryl” refers to a 5- to6-membered heteroaryl ring having 1 to 3 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur, or an 8- to 14-memberedpolycyclic heteroaryl ring having 1 to 4 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur.

As used herein, the terms “heterocycle”, “heterocyclyl”, “heterocyclicradical”, and “heterocyclic ring” are used interchangeably and refer toa stable 5- to 7-membered monocyclic or 7- to 14-membered bicyclicheterocyclic moiety that is either saturated or partially unsaturated,and having, in addition to carbon atoms, one or more, preferably one tofour, heteroatoms, as defined above. When used in reference to a ringatom of a heterocycle, the term “nitrogen” includes a substitutednitrogen. As an example, in a saturated or partially unsaturated ringhaving 0-3 heteroatoms selected from oxygen, sulfur or nitrogen, thenitrogen may be N (as in 3,4-dihydro-2H-pyrrolyl), NH (as inpyrrolidinyl), or ⁺NR (as in N-substituted pyrrolidinyl). In someembodiments, the term “3- to 7-membered heterocyclic” refers to a 3- to7-membered saturated or partially unsaturated monocyclic heterocyclicring having 1 to 2 heteroatoms independently selected from nitrogen,oxygen, or sulfur. In some embodiments, the term “3- to 8-memberedheterocycle” refers to a 3- to 8-membered saturated or partiallyunsaturated monocyclic heterocyclic ring having 1 to 2 heteroatomsindependently selected from nitrogen, oxygen, or sulfur. In someembodiments, the term “3- to 12-membered heterocyclic” refers to a 3- to8-membered saturated or partially unsaturated monocyclic heterocyclicring having 1 to 2 heteroatoms independently selected from nitrogen,oxygen, or sulfur, or a 7- to 12-membered saturated or partiallyunsaturated polycyclic heterocyclic ring having 1-3 heteroatomsindependently selected from nitrogen, oxygen, or sulfur. In someembodiments, the term “3- to 14-membered heterocycle” refers to a 3- to8-membered saturated or partially unsaturated monocyclic heterocyclicring having 1 to 2 heteroatoms independently selected from nitrogen,oxygen, or sulfur, or a 7- to 14-membered saturated or partiallyunsaturated polycyclic heterocyclic ring having 1-3 heteroatomsindependently selected from nitrogen, oxygen, or sulfur.

A heterocyclic ring can be attached to its pendant group at anyheteroatom or carbon atom that results in a stable structure and any ofthe ring atoms can be optionally substituted. Examples of such saturatedor partially unsaturated heterocyclic radicals include, withoutlimitation, tetrahydrofuranyl, tetrahydrothienyl, pyrrolidinyl,pyrrolidonyl, piperidinyl, pyrrolinyl, tetrahydroquinolinyl,tetrahydroisoquinolinyl, decahydroquinolinyl, oxazolidinyl, piperazinyl,dioxanyl, dioxolanyl, diazepinyl, oxazepinyl, thiazepinyl, morpholinyl,and quinuclidinyl. The terms “heterocycle”, “heterocyclyl”,“heterocyclyl ring”, “heterocyclic group”, “heterocyclic moiety”, and“heterocyclic radical”, are used interchangeably herein, and alsoinclude groups in which a heterocyclyl ring is fused to one or morearyl, heteroaryl, or cycloaliphatic rings, such as indolinyl,3H-indolyl, chromanyl, phenanthridinyl, or tetrahydroquinolinyl, wherethe radical or point of attachment is on the heterocyclyl ring. Aheterocyclyl group may be mono- or bicyclic. The term“heterocyclylalkyl” refers to an alkyl group substituted by aheterocyclyl, wherein the alkyl and heterocyclyl portions independentlyare optionally substituted.

As used herein, the term “partially unsaturated” refers to a ring moietythat includes at least one double or triple bond. The term “partiallyunsaturated” is intended to encompass rings having multiple sites ofunsaturation, but is not intended to include aryl or heteroarylmoieties, as herein defined.

One of ordinary skill in the art will appreciate that the syntheticmethods, as described herein, may utilize a variety of protectinggroups. By the term “protecting group,” as used herein, it is meant thata particular functional moiety, e.g., O, S, or N, is masked or blocked,permitting, if desired, a reaction to be carried out selectively atanother reactive site in a multifunctional compound. In someembodiments, a protecting group reacts selectively in good yield to givea protected substrate that is stable to the projected reactions; theprotecting group is preferably selectively removable by readilyavailable, preferably non-toxic reagents that do not attack the otherfunctional groups; the protecting group forms a separable derivative(more preferably without the generation of new stereogenic centers); andthe protecting group will preferably have a minimum of additionalfunctionality to avoid further sites of reaction. By way of non-limitingexample, hydroxyl protecting groups include methyl, methoxylmethyl(MOM), methylthiomethyl (MTM), t-butylthiomethyl,(phenyldimethylsilyl)methoxymethyl (SMOM), benzyloxymethyl (BOM),p-methoxybenzyloxymethyl (PMBM), (4-methoxyphenoxy)methyl (p-AOM),guaiacolmethyl (GUM), t-butoxymethyl, 4-pentenyloxymethyl (POM),siloxymethyl, 2-methoxyethoxymethyl (MEM), 2,2,2-trichloroethoxymethyl,bis(2-chloroethoxy)methyl, 2-(trimethylsilyl)ethoxymethyl (SEMOR),tetrahydropyranyl (THP), 3-bromotetrahydropyranyl,tetrahydrothiopyranyl, 1-methoxycyclohexyl, 4-methoxytetrahydropyranyl(MTHP), 4-methoxytetrahydrothiopyranyl, 4-methoxytetrahydrothiopyranylS,S-dioxide, 1-[(2-chloro-4-methyl)phenyl]-4-methoxypiperidin-4-yl(CTMP), 1,4-dioxan-2-yl, tetrahydrofuranyl, tetrahydrothiofuranyl,2,3,3a,4,5,6,7,7a-octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-yl,1-ethoxyethyl, 1-(2-chloroethoxy)ethyl, 1-methyl-1-methoxyethyl,1-methyl-1-benzyloxyethyl, 1-methyl-1-benzyloxy-2-fluoroethyl,2,2,2-trichloroethyl, 2-trimethylsilylethyl, 2-(phenylselenyl)ethyl,t-butyl, allyl, p-chlorophenyl, p-methoxyphenyl, 2,4-dinitrophenyl,benzyl, p-methoxybenzyl, 3,4-dimethoxybenzyl, o-nitrobenzyl,p-nitrobenzyl, p-halobenzyl, 2,6-dichlorobenzyl, p-cyanobenzyl,p-phenylbenzyl, 2-picolyl, 4-picolyl, 3-methyl-2-picolyl N-oxido,diphenylmethyl, p,p′-dinitrobenzhydryl, 5-dibenzosuberyl,triphenylmethyl, a-naphthyldiphenylmethyl,p-methoxyphenyldiphenylmethyl, di(p-methoxyphenyl)phenylmethyl,tri(p-methoxyphenyl)methyl, 4-(4′-bromophenacyloxyphenyl)diphenylmethyl,4,4′,4″-tris(4,5-dichlorophthalimidophenyl)methyl,4,4′,4″-tris(levulinoyloxyphenyl)methyl,4,4′,4″-tris(benzoyloxyphenyl)methyl,3-(imidazol-1-yl)bis(4′,4″-dimethoxyphenyl)methyl,1,1-bis(4-methoxyphenyl)-1′-pyrenylmethyl, 9-anthryl,9-(9-phenyl)xanthenyl, 9-(9-phenyl-10-oxo)anthryl,1,3-benzodithiolan-2-yl, benzisothiazolyl S,S-dioxido, trimethylsilyl(TMS), triethylsilyl (TES), triisopropylsilyl (TIPS),dimethylisopropylsilyl (IPDMS), diethylisopropylsilyl (DEIPS),dimethylthexylsilyl, t-butyldimethylsilyl (TBDMS), t-butyldiphenylsilyl(TBDPS), tribenzylsilyl, tri-p-xylylsilyl, triphenylsilyl,diphenylmethylsilyl (DPMS), t-butylmethoxyphenylsilyl (TBMPS), formate,benzoylformate, acetate, chloroacetate, dichloroacetate,trichloroacetate, trifluoroacetate, methoxyacetate,triphenylmethoxyacetate, phenoxyacetate, p-chlorophenoxyacetate,3-phenylpropionate, 4-oxopentanoate (levulinate),4,4-(ethylenedithio)pentanoate (levulinoyldithioacetal), pivaloate,adamantoate, crotonate, 4-methoxycrotonate, benzoate, p-phenylbenzoate,2,4,6-trimethylbenzoate (mesitoate), alkyl methyl carbonate,9-fluorenylmethyl carbonate (Fmoc), alkyl ethyl carbonate, alkyl2,2,2-trichloroethyl carbonate (Troc), 2-(trimethylsilyl)ethyl carbonate(TMSEC), 2-(phenylsulfonyl) ethyl carbonate (Psec),2-(triphenylphosphonio) ethyl carbonate (Peoc), alkyl isobutylcarbonate, alkyl vinyl carbonate alkyl allyl carbonate, alkylp-nitrophenyl carbonate, alkyl benzyl carbonate, alkyl p-methoxybenzylcarbonate, alkyl 3,4-dimethoxybenzyl carbonate, alkyl o-nitrobenzylcarbonate, alkyl p-nitrobenzyl carbonate, alkyl S-benzyl thiocarbonate,4-ethoxy-1-naphthyl carbonate, methyl dithiocarbonate, 2-iodobenzoate,4-azidobutyrate, 4-nitro-4-methylpentanoate, o-(dibromomethyl)benzoate,2-formylbenzenesulfonate, 2-(methylthiomethoxy)ethyl,4-(methylthiomethoxy)butyrate, 2-(methylthiomethoxymethyl)benzoate,2,6-dichloro-4-methylphenoxyacetate,2,6-dichloro-4-(1,1,3,3-tetramethylbutyl)phenoxyacetate,2,4-bis(1,1-dimethylpropyl)phenoxyacetate, chlorodiphenylacetate,isobutyrate, monosuccinoate, (E)-2-methyl-2-butenoate,o-(methoxycarbonyl)benzoate, α-naphthoate, nitrate, alkylN,N,N′,N′-tetramethylphosphorodiamidate, alkyl N-phenylcarbamate,borate, dimethylphosphinothioyl, alkyl 2,4-dinitrophenylsulfenate,sulfate, methanesulfonate (mesylate), benzylsulfonate, and tosylate(Ts). Exemplary protecting groups are detailed herein, however, it willbe appreciated that the present disclosure is not intended to be limitedto these protecting groups; rather, a variety of additional equivalentprotecting groups can be readily identified using the above criteria andutilized in the method of the present disclosure. Additionally, avariety of protecting groups are described by Greene and Wuts (infra).

As described herein, compounds of the invention may contain “optionallysubstituted” moieties. In general, the term “substituted”, whetherpreceded by the term “optionally” or not, means that one or morehydrogens of the designated moiety are replaced with a suitablesubstituent. Unless otherwise indicated, an “optionally substituted”group may have a suitable substituent at each substitutable position ofthe group, and when more than one position in any given structure may besubstituted with more than one substituent selected from a specifiedgroup, the substituent may be either the same or different at everyposition. Combinations of substituents envisioned by this invention arepreferably those that result in the formation of stable or chemicallyfeasible compounds. The term “stable”, as used herein, refers tocompounds that are not substantially altered when subjected toconditions to allow for their production, detection, and, in certainembodiments, their recovery, purification, and use for one or more ofthe purposes disclosed herein.

Suitable monovalent substituents on a substitutable carbon atom of an“optionally substituted” group are independently halogen;—(CH₂)₀₋₄R^(∘); —(CH₂)₀₋₄OR^(∘); —O—(CH₂)₀₋₄C(O)OR^(∘);—(CH₂)₀₋₄CH(OR^(∘))₂; —(CH₂)₀₋₄SR^(∘); —(CH₂)₀₋₄Ph, which may besubstituted with R^(∘); —(CH₂)₀₋₄O(CH₂)₀₋₁Ph which may be substitutedwith R^(∘); —CH═CHPh, which may be substituted with R^(∘); —NO₂; —CN;—N₃; —(CH₂)₀₋₄N(R^(∘))₂; —(CH₂)₀₋₄N(R^(∘))C(O)R^(∘); —N(R^(∘))C(S)R^(∘);—(CH₂)₀₋₄N(R^(∘))C(O)NR^(∘) ₂; —N(R^(∘))C(S)NR^(∘) ₂;—(CH₂)₀₋₄N(R^(∘))C(O)OR^(∘); —N(R^(∘))N(R^(∘))C(O)R^(∘);—N(R^(∘))N(R^(∘))C(O)NR^(∘) ₂; —N(R^(∘))N(R^(∘))C(O)OR^(∘);—(CH₂)₀₋₄C(O)R^(∘); —C(S)R^(∘); —(CH₂)₀₋₄C(O)OR^(∘);(CH₂)₀₋₄C(O)N(R^(∘))₂; —(CH₂)₀₋₄C(O)SR^(∘); —(CH₂)₀₋₄C(O)OSiR^(∘) ₃;—(CH₂)₀₋₄OC(O)R^(∘); —OC(O)(CH₂)₀₋₄SR—, SC(S)SR^(∘);—(CH₂)₀₋₄SC(O)R^(∘); —(CH₂)₀₋₄C(O)NR^(∘) ₂; —C(S)NR^(∘) ₂; —C(S)SR^(∘);—SC(S)SR^(∘), —(CH₂)₀₋₄OC(O)NR^(∘) ₂; —C(O)N(OR^(∘))R^(∘);—C(O)C(O)R^(∘); —C(O)CH₂C(O)R^(∘); —C(NOR^(∘))R^(∘); —(CH₂)₀₋₄SSR^(∘);—(CH₂)₀₋₄S(O)₂R^(∘); —(CH₂)₀₋₄S(O)₂OR^(∘); —(CH₂)₀₋₄OS(O)₂R^(∘);—S(O)₂NR^(∘) ₂; —(CH₂)₀₋₄S(O)R^(∘); —N(R^(∘))S(O)₂NR^(∘) ₂;—N(R^(∘))S(O)₂R^(∘); N(OR^(∘))R^(∘); —C(NH)NR^(∘) ₂; —P(O)₂R^(∘);—P(O)R^(∘) ₂; —OP(O)R^(∘) ₂; —OP(O)(OR^(∘))₂; SiR^(∘) ₃; —(C₁₋₄ straightor branched alkylene)O—N(R^(∘))₂; or —(C₁₋₄ straight or branchedalkylene)C(O)O—N(R^(∘))₂, wherein each R^(∘) may be substituted asdefined below and is independently hydrogen, C₁₋₈ aliphatic, —CH₂Ph,—O(CH₂)₀₋₁Ph, or a 5-6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur, or, notwithstanding the definition above, twoindependent occurrences of R^(∘), taken together with their interveningatom(s), form a 3- to 12-membered saturated, partially unsaturated, oraryl mono- or polycyclic ring having 0-4 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur, which may be substituted asdefined below.

Suitable monovalent substituents on R^(∘) (or the ring formed by takingtwo independent occurrences of R^(∘) together with their interveningatoms), are independently halogen, —(CH₂)₀₋₂R^(●), -(haloR^(●)),—(CH₂)₀₋₂OH, —(CH₂)₀₋₂OR^(●), —(CH₂)₀₋₂CH(OR^(●))₂; —O(haloR^(●)), —CN,—N₃, —(CH₂)₀₋₂C(O)R^(●), —(CH₂)₀₋₂C(O)OH, —(CH₂)₀₋₂C(O)OR^(●),—(CH₂)₀₋₄C(O)N(R^(∘))₂; —(CH₂)₀₋₂SR^(●), —(CH₂)₀₋₂SH, —(CH₂)₀₋₂NH₂,—(CH₂)₀₋₂NHR^(●), —(CH₂)₀₋₂NR^(●) ₂, —NO₂, —SiR^(●) ₃, —OSiR^(●) ₃,—C(O)SR^(●), —(C₁₋₄ straight or branched alkylene)C(O)OR^(●), or—SSR^(●) wherein each R^(●) is unsubstituted or where preceded by “halo”is substituted only with one or more halogens, and is independentlyselected from C₁₋₄ aliphatic, —CH₂Ph, —O(CH₂)₀₋₁Ph, or a 5- to6-membered saturated, partially unsaturated, or aryl ring having 0-4heteroatoms independently selected from nitrogen, oxygen, or sulfur.Suitable divalent substituents on a saturated carbon atom of R^(∘)include ═O and ═S.

Suitable divalent substituents on a saturated carbon atom of an“optionally substituted” group include the following: ═O, ═S, ═NNR*₂,═NNHC(O)R*, ═NNHC(O)OR*, ═NNHS(O)₂R*, ═NR*, ═NOR*, —O(C(R*₂))₂₋₃O—, or—S(C(R*₂))₂₋₃S—, wherein each independent occurrence of R* is selectedfrom hydrogen, C₁₋₆ aliphatic which may be substituted as defined below,or an unsubstituted 5-6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur. Suitable divalent substituents that are bound tovicinal substitutable carbons of an “optionally substituted” groupinclude: —O(CR*₂)₂₋₃O—, wherein each independent occurrence of R* isselected from hydrogen, C₁₋₆ aliphatic which may be substituted asdefined below, or an unsubstituted 5- to 6-membered saturated, partiallyunsaturated, or aryl ring having 0-4 heteroatoms independently selectedfrom nitrogen, oxygen, or sulfur.

Suitable substituents on the aliphatic group of R* include halogen,—R^(●), -(haloR^(●)), —OH, —OR^(●), —O(haloR^(●)), —CN, —C(O)OH,—C(O)OR^(●), —NH₂, —NHR^(●), —NR^(●) ₂, or —NO₂, wherein each R^(●) isunsubstituted or where preceded by “halo” is substituted only with oneor more halogens, and is independently C₁₋₄ aliphatic, —CH₂Ph,—O(CH₂)₀₋₁Ph, or a 5- to 6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur.

Suitable substituents on a substitutable nitrogen of an “optionallysubstituted” group include —R^(†), —NR^(†) ₂, —C(O)R^(†), —C(O)OR^(†),—C(O)C(O)R^(†), —C(O)CH₂C(O)R^(†), —S(O)₂R^(†), —S(O)₂NR^(†) ₂,—C(S)NR^(†) ₂, —C(NH)NR^(†) ₂, or —N(R^(†))S(O)₂R^(†); wherein eachR^(†) is independently hydrogen, C₁₋₆ aliphatic which may be substitutedas defined below, unsubstituted —OPh, or an unsubstituted 5- to6-membered saturated, partially unsaturated, or aryl ring having 0-4heteroatoms independently selected from nitrogen, oxygen, or sulfur, or,notwithstanding the definition above, two independent occurrences ofR^(†), taken together with their intervening atom(s) form anunsubstituted 3- to 12-membered saturated, partially unsaturated, oraryl mono- or bicyclic ring having 0-4 heteroatoms independentlyselected from nitrogen, oxygen, or sulfur.

Suitable substituents on the aliphatic group of R^(†) are independentlyhalogen, —R^(●),-(haloR^(●)), —OH, —OR^(●), —O(haloR^(●)), —CN, —C(O)OH,—C(O)OR^(●), —NH₂, —NHR^(●), —NR^(●) ₂, or —NO₂, wherein each R^(●) isunsubstituted or where preceded by “halo” is substituted only with oneor more halogens, and is independently C₁₋₄ aliphatic, —CH₂Ph,—O(CH₂)₀₋₁Ph, or a 5- to 6-membered saturated, partially unsaturated, oraryl ring having 0-4 heteroatoms independently selected from nitrogen,oxygen, or sulfur.

In some chemical structures herein, substituents are shown attached to abond which crosses another bond of a depicted molecule. This means thatone or more of the substituents may be attached to the molecule at anyavailable position (usually in place of a hydrogen atom of the parentstructure). In cases where an atom of a molecule so substituted has twosubstitutable positions, two groups may be present on the same ringatom. When more than one substituent is present, each is definedindependently of the others, and each may have a different structure. Incases where the substituent shown crossing a bond of the molecule is —R,this has the same meaning as if the ring were said to be “optionallysubstituted” as described in the preceding paragraphs.

As used herein, the terms “head-to-tail” or “HT”, refer to theregiochemistry of adjacent repeating units in a polymer chain. Forexample, in the context of poly(propylene carbonate), the termhead-to-tail based on the three regiochemical possibilities depictedbelow:

The term head-to-tail ratio (H:T) refers to the proportion ofhead-to-tail linkages to the sum of all other regiochemicalpossibilities.

As used herein, the term “mixture,” when applied to a substituent, meansthat the substituent varies throughout the molecule and not alloccurrences are the same (i.e., it refers to a plurality of thesubstituent rather than a single occurrence of the substituent). Forexample, “R¹ is a mixture of methyl, ethyl, and propyl groups” will beunderstood to mean “R¹ is selected from the group consisting of methyl,ethyl, and propyl, wherein not all occurrences of R¹ are the same.”

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts supercritical CO₂ solubility of a composition of thepresent invention comprising a diblock copolymer of poly(propylenecarbonate) (PPC) and poly(ethylene glycol) (PEG).

FIG. 2 depicts supercritical CO₂ solubility of a composition of thepresent invention comprising a diblock copolymer of PPC and PEG.

FIG. 3 depicts supercritical CO₂ solubility of a composition of thepresent invention comprising a diblock copolymer of PPC and PEG.

FIG. 4 depicts supercritical CO₂ solubility of a composition of thepresent invention comprising a triblock copolymer of PPC and PEG.

FIG. 5 shows the stability over time of CO₂/water foams stabilized byPPC/PEG diblock co-polymers (28-34A) and PPC/PEG/PPC triblock copolymers(28-53B -53C and -53D) of the present invention where the bottom half ofthe y-axis represents the depth of foam in the aqueous phase, and theupper half of the y-axis represents the height of foam in thesupercritical CO₂ phase.

FIG. 6 shows the stability over time of CO₂/water foams stabilized byPPC/PPG/PPC triblock copolymers of the present invention where eachblock in the copolymer comprises between 3 and 12 repeat units.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The present disclosure encompasses the recognition that block copolymerscomprising a polycarbonate chain have utility in a number ofapplications involving interaction with CO₂. In some embodiments, thepresent disclosure provides copolymers and compositions thereofcomprising a polycarbonate or a polyether-polycarbonate chain, methodsof making, and methods of using the same.

In certain embodiments, provided block copolymers of formula A-L-B,where A- is a polycarbonate or a polyether-polycarbonate chain havingfrom about 3 to about 500 repeating units, L is a linker moiety or acovalent bond and -B is a hydrophilic oligomer having from about 4 toabout 500 repeating units.

In some embodiments, A- is a polycarbonate chain. In some embodiments,A- is a polycarbonate chain containing greater than about 95%, greaterthan about 98%, or greater than about 99% carbonate linkages. In someembodiments, A- is an aliphatic polycarbonate chain. In certainembodiments, the aliphatic polycarbonate is a copolymer of an optionallysubstituted epoxide and carbon dioxide. In certain embodiments, thepolycarbonate is selected from the group consisting of poly(ethylenecarbonate), poly(propylene carbonate), poly(butylene carbonate),poly(glycidylether carbonate), poly(chloromethylethylene carbonate),poly(cyclopentene carbonate), poly(cyclohexene carbonate), poly(3-vinylcyclohexene carbonate) and random-, block- or tapered-copolymers of anytwo or more of the above.

In certain embodiments, a polycarbonate chain A- is poly(propylenecarbonate). In certain embodiments, a polycarbonate chain A- ispoly(ethylene carbonate). In certain embodiments, a polycarbonate chainA- is poly(chloromethylethylene carbonate). In certain embodiments, apolycarbonate chain A- is poly(butylene carbonate). In certainembodiments, a polycarbonate chain A- is a poly(glycidyl ethercarbonate). In certain embodiments, a polycarbonate chain A- is apoly(glycidyl ester carbonate). In certain embodiments, a polycarbonatechain A- is a random copolymer comprising poly(propylene carbonate) andpoly(ethylene carbonate). In some embodiments, a polycarbonate chain A-is a random copolymer comprising poly(propylene carbonate) andpoly(n-butylene carbonate). In certain embodiments, a polycarbonatechain A- is a random copolymer comprising poly(propylene carbonate) anda polycarbonate derived from the epoxide of a C₆₋₃₀ alpha olefin.

In certain embodiments, a polycarbonate chain A- includes about 3 toabout 500 repeating units. In certain embodiments, a polycarbonate chainincludes about 5 to about 50 repeating units. In certain embodiments, apolycarbonate chain includes about 3 to about 20 repeating units. Incertain embodiments, a polycarbonate chain includes about 10 to about 15repeating units. In certain embodiments, a polycarbonate chain includesabout 20 to about 50 repeating units.

In some embodiments, a polymer chain A- is a random or tapered polyetherpolycarbonate copolymer. In certain embodiments, the proportion of etherlinkages in a polyether polycarbonate chain A- ranges from about 0.1% toabout 50%. In certain embodiments, the proportion of ether linkages in apolyether polycarbonate chain A-ranges from about 0.1% to about 44%. Incertain embodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 43%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 42%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 41%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 40%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 35%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 30%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 25%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 20%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 15%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 10%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 5%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 2%.

In certain embodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- is less than 50%. In certain embodiments, theproportion of ether linkages in a polyether polycarbonate chain A- isless than 44%. In certain embodiments, the proportion of ether linkagesin a polyether polycarbonate chain A- is less than 43%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- is less than 42%. In certain embodiments, theproportion of ether linkages in a polyether polycarbonate chain A- isless than 41%. In certain embodiments, the proportion of ether linkagesin a polyether polycarbonate chain A- is less than 40%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- is less than 35%. In certain embodiments, theproportion of ether linkages in a polyether polycarbonate chain A- isless than 30%. In certain embodiments, the proportion of ether linkagesin a polyether polycarbonate chain A- is less than 25%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- is less than 20%. In certain embodiments, theproportion of ether linkages in a polyether polycarbonate chain A- isless than 15%. In certain embodiments, the proportion of ether linkagesin a polyether polycarbonate chain A- is less than 10%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- is less than 9%. In certain embodiments, theproportion of ether linkages in a polyether polycarbonate chain A- isless than 8%. In certain embodiments, the proportion of ether linkagesin a polyether polycarbonate chain A- is less than 7%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- is less than 6%. In certain embodiments, theproportion of ether linkages in a polyether polycarbonate chain A- isless than 5%. In certain embodiments, the proportion of ether linkagesin a polyether polycarbonate chain A- is less than 4%. In certainembodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- is less than 3%. In certain embodiments, theproportion of ether linkages in a polyether polycarbonate chain A- isless than 2%. In certain embodiments, the proportion of ether linkagesin a polyether polycarbonate chain A- is less than 1%.

In certain embodiments, the proportion of ether linkages in a polyetherpolycarbonate chain A- ranges from about 0.1% to about 25%. In certainembodiments the proportion of ether linkages in a polyetherpolycarbonate chain A- is less than about 10%. In certain embodimentsthe proportion of ether linkages in a polyether polycarbonate chain A-ranges from about 1% to about 5%. In certain embodiments, the proportionof ether linkages in a polyether polycarbonate chain A- ranges fromabout 20% to about 50%.

In certain embodiments, L is a covalent bond (i.e. A- is bonded directlyto -B). In other embodiments, L is a polyfunctional moiety havingappropriate functionality to form a covalent chemical bond with both thepolycarbonate chain and the hydrophilic oligomer. In certain instances,L is a moiety formed by the reaction of one functional group on A- andone functional group on -B with a polyfunctional molecule capable ofreaction with the functional groups on A- and -B thereby linking them.Examples of suitable polyfunctional moieties for L include, but are notlimited to: agents that can form one or more linkages such as ester,amide, ether, amine, thioether, carbonate, or other similar linkages.Examples of polyfunctional molecules suitable for incorporation as Linclude, but are not limited to: phosgene, diacids, anhydrides,acrylates, diisocyanates, epoxides, diols, diamines, hydroxy mercaptans,mercapto acids, hydroxy acids, amino acids, and any precursors orreactive equivalents thereof.

In certain embodiments, a linker L is a moiety formed directly by thereaction of complementary functional groups on termini of A- and -B.Examples of such moieties include, but are not limited to: L being anester, (formed from an alcohol group on the terminus of A- and a carboxygroup on the terminus of -B, or vice versa); L being an amide; (formedfrom an amine group on the terminus of A- and a carboxy group on theterminus of -B, or vice versa); L being an olefin (formed, for example,by olefin metathesis); L being a heterocycle, (for example a triazoleformed by cycloaddition of an azide and an alkyne), and L being acyclohexene ring formed by Diels Alder cycloaddition of a diene and adienophile.

In certain embodiments, a hydrophilic oligomer -B is a polyether chain.In some embodiments, -B is a polyolefin chain bearing hydrophilicfunctional groups. In certain embodiments, a hydrophilic oligomer -B isa polyamine chain. In certain embodiments,-B is selected from the groupconsisting of polyoxymethylene, poly(ethylene oxide), poly(propyleneoxide), polyvinyl alcohol, poly(vinyl acetate), partially hydrolyzedpoly(vinyl acetate), poly(acrylic acid), polyacrylamide,polyethyleneimine, poly(2-hydroxyethyl methacrylate),poly(N-vinylpyrrolidone), polypeptides, polysaccharides,polyepoxysuccinic acid, poly(methyl vinyl ether), poly(allylamine),poly(2-ethyl-2-oxazoline), and block, tapered or random copolymers ofany two or more of the above. In some embodiments, -B ispolyoxymethylene. In some embodiments, -B is poly(ethylene oxide). Insome embodiments, -B is poly(propylene oxide).

In certain embodiments, a hydrophilic oligomer -B includes from about 4to about 400 repeating units. In certain embodiments, a hydrophilicoligomer chain includes less than about 100 repeating units. In certainembodiments, a hydrophilic oligomer chain includes about 10 to about 50repeating units. In certain embodiments, a hydrophilic oligomer chainincludes about 10 to about 20 repeating units.

In certain embodiments, polymers of the present invention have a totalaverage molecular weight between about 300 g/mol and about 25,000 g/mol.In certain embodiments, polymers have a total average molecular weightbetween about 500 g/mol and about 5,000 g/mol. In some embodiments,polymers have a total average molecular weight between about 800 g/moland about 2,500 g/mol.

polycarbonates

In certain embodiments, a polymer A-L-B has the formula I:

-   where X is selected from the group consisting of: halogen; —OH;    azide, nitrile, and —OR^(z);-   each R^(a), R^(b), R^(c), and R^(d) is independently selected from    the group consisting of: hydrogen, halogen, —CH₂OR^(z), optionally    substituted C₁₋₃₀ aliphatic, optionally substituted 6- to    14-membered aromatic, optionally substituted 3- to 14-membered    heterocyclic, and optionally substituted 5- to 14-membered    heteroaryl, where any two or more of R^(a), R^(b), R^(c), and R^(d)    may be taken together to form an optionally substituted 3- to    12-membered ring, optionally containing one or more heteroatoms;-   L is a bond or a polyfunctional moiety;-   B is a hydrophilic oligomer having from 4 to 100 repeating units;-   n is an integer between 3 and 100;-   R^(z) is selected from the group consisting of R¹⁰, C(O)R¹⁰,    —SO₂R¹⁰, —Si(R¹⁰)₃, and —C(O)N(R¹⁰)₂; and-   R¹⁰ is an optionally substituted moiety selected from the group    consisting of: C₁₋₂₀ aliphatic; C₁₋₁₂ heteroaliphatic; 6- to    14-membered aryl; and 5- to 14-membered heteroaryl.

In certain embodiments, polymers of formula I comprise a polycarbonatechain containing greater than about 90% carbonate linkages. In certainembodiments, the polycarbonate chain contains greater than about 95%,greater than about 98%, or greater than about 99% carbonate linkages. Incertain embodiments, the polycarbonate chain contains essentially nodetectable ether linkages.

In certain embodiments, the polymer A-L-B has the formula I-a:

-   X, L, B, and n are as defined above, and-   R¹⁰⁰ is optionally present, and if present is selected from the    group consisting of CH₃, —CF₃, —CH₂CH₃, —CH₂OR^(z), —CH₂Cl, a C₃₋₃₀    alkyl group, and mixtures of two or more of these where R^(z) is as    defined above.

In certain embodiments, a polymer A-L-B has the formula I-b:

X, L, B, R¹⁰⁰, and n are as defined above.

In certain embodiments, a polymer A-L-B has formula I-c:

L, B, R¹⁰⁰, and n are as defined above, and X′ is selected from thegroup consisting of —OH and —OR^(z).

In certain embodiments, where a polymer has one of the formulae I-b orI-c, where R¹⁰⁰ is present, the head to tail ratio of adjacent

groups is greater than about 80%. In certain embodiments, the head totail ratio is greater than about 90%. In certain embodiments, the headto tail ratio is greater than about 91%. In certain embodiments, thehead to tail ratio is greater than about 92%. In certain embodiments,the head to tail ratio is greater than about 93%. In certainembodiments, the head to tail ratio is greater than about 94%. Incertain embodiments, the head to tail ratio is greater than about 95%.

In certain embodiments, in polymers of formulae I-a through I-c R¹⁰⁰ isabsent (e.g. the polycarbonate chain comprises poly(ethylene carbonate).In certain embodiments, in polymers of formulae I-a through I-c, R¹⁰⁰ isa methyl group. In certain embodiments, in polymers of formulae I-athrough I-c, R¹⁰⁰ is a C₃₋₃₀ alkyl group. In certain embodiments, inpolymers of formulae I-a through I-c, R¹⁰⁰ is a C₃₋₁₀ alkyl group. Incertain embodiments, in polymers of formulae I-a through I-c, R¹⁰⁰ is aC₃₋₆ alkyl group. In certain embodiments, in polymers of formulae I-athrough I-c, R¹⁰⁰ is an ethyl group. In certain embodiments, in polymersof formulae I-a through I-c, R¹⁰⁰ is a chloromethyl group. In certainembodiments, in polymers of formulae I-a through I-c, R¹⁰⁰ is a randommixture of methyl and ethyl groups. In certain embodiments, in polymersof formulae I-a through I-c, R¹⁰⁰ is a random mixture of methyl andchloromethyl groups. In certain embodiments, in polymers of formulae I-athrough I-c, R¹⁰⁰ is a random mixture of methyl and one or more C₃₋₃₀alkyl groups.

In certain embodiments, in polymers of formulae I-a through I-c, R¹⁰⁰ isa —CH₂OR^(z) group. In certain embodiments, the CH₂OR^(z) groupcomprises an ether group (e.g. the polycarbonate chain is apoly(glycidyl ether carbonate)). In other embodiments the CH₂OR^(z)group comprises an ester group (e.g. the polycarbonate chain is apoly(glycidyl ester carbonate)). In certain embodiments, R¹⁰⁰ is arandom mixture of C₃₋₃₀ alkyl and —CH₂OR^(z) groups.

In certain embodiments, for polymers of formula I-b, X is —OR¹⁰. Inother embodiments, for polymers of formula I-b, X is —OC(O)R¹⁰. Incertain embodiments, for polymers of formula I-b, X is Cl, or Br. Incertain embodiments, for polymers of formula I-b, X is azide or anitrile. In certain embodiments, for polymers of formula I-b, X isacetate. In certain embodiments, for polymers of formula I-b, X istrifluoroacetate. In certain embodiments, for polymers of formula I-b, Xis optionally substituted benzoate. In certain embodiments, for polymersof formulae I-b, X is optionally substituted phenoxide. In certainembodiments, for polymers of formulae I-b, X is a nitro phenoxide.

In certain embodiments, for polymers of formulae I-c, X′ is —OH. Incertain embodiments, for polymers of formulae I-c, X′ is —OR^(y), whereR^(y) is an —OH protecting group. In certain embodiments, for polymersof formulae I-c, X′ is —OC(O)R¹⁰. In certain embodiments, for polymersof formulae I-c, X′ is —OS(O)₂R¹⁰. In certain embodiments, for polymersof formulae I-c, X′ is —OSi(R¹⁰)₃. In certain embodiments, for polymersof formulae I-c, X′ is —OC(O)N(R¹⁰)₂. In certain embodiments, forpolymers of formulae I-c, X′ is acetate. In certain embodiments, forpolymers of formulae I-c, X′ is trifluoroacetate. In certainembodiments, for polymers of formulae I-c, X′ is optionally substitutedbenzyl or benzoate.

The present invention encompasses polymer compositions comprisingpolymer chains of formulae I through I-c above wherein the value of nis, on average, between about 5 and about 200. In certain embodiments,the value of n is, on average between about 5 and about 100. In certainembodiments, the value of n is, on average between about 5 and about 50.In certain embodiments, the value of n is, on average between about 5and about 25. In certain embodiments, the value of n is, on averagebetween about 5 and about 10. In certain embodiments, the value of n is,on average between about 10 and about 20.

In certain embodiments, a polymer A-L-B has the formula II:

where A and L are as defined above,m is an integer between about 4 and about 500,—Z— is an optionally substituted C₁₋₆ aliphatic group, and—Y is selected from the group consisting of —H and R^(z).

In certain embodiments, a polymer A-L-B has the formula II-a:

where X, R^(a), R^(b), R^(c), R^(d), n, L, Z, m, and Y are as definedabove.

In certain embodiments, a polymer A-L-B has the formula II-b:

where X, R¹⁰⁰, n, L, Z, m, and Y are as defined above.

In certain embodiments, a polymer A-L-B has the formula II-c:

where R¹⁰⁰, n, L, Z, and m are as defined above and wherein X is otherthan —OH.

In certain embodiments, a polymer A-L-B has the formula II-d:

-   where X′, R¹⁰⁰, n, L, Z, and m are as defined above, and Y′ is    optionally substituted C₁₋₈ aliphatic, a silyl protecting group, or    —C(O)R¹¹, wherein R¹¹ is optionally substituted C₁₋₁₄ aliphatic or    6- to 14-membered aryl.

In certain embodiments, for polymers of formulae II through II-d, Z is—CH₂— (e.g. the hydrophilic oligomer -B is polyoxymethylene). In certainembodiments, for polymers of formulae II through II-d, Z is —CH₂CH₂—(e.g. the hydrophilic oligomer -B is polyethylene glycol). In certainembodiments, for polymers of formulae II through II-d, Z is —CH(CH₃)CH₂—(e.g. the hydrophilic oligomer -B is polypropylene glycol).

In certain embodiments, in polymers of formulae II, II-a, or II-b, —Y isan optionally substituted C₁₋₂₀ aliphatic group. In certain embodiments,Y is selected from the group consisting of methyl, ethyl, n-propyl,i-propyl, n-butyl, sec-butyl, t-butyl, allyl and benzyl. In certainembodiments, in polymers of formulae II, II-a or II-b, —Y is an acylgroup. In certain embodiments, Y is selected from the group consistingof formate, acetate, trifluoroacetate, propionate, butyrate, acrylate,and optionally substituted benzoate. In certain embodiments, in polymersof formulae II, II-a or II-b, —Y is —Si(R¹⁰)₃. In certain embodiments,in polymers of formulae II, II-a or II-b, —Y is a silyl protectinggroup. In certain embodiments, Y is selected from the group consistingof trimethylsilyl, triethylsilyl, triisopropyl silyl,t-butyldimethylsilyl, and t-butyldiphenylsilyl. In certain embodiments,in polymers of formulae II, II-a or II-b, —Y is —H.

In certain embodiments, in polymers of formulae II-b through II-d, R¹⁰⁰is absent (e.g. the polycarbonate chain comprises poly(ethylenecarbonate). In certain embodiments, in polymers of formulae II-b throughII-d, R¹⁰⁰ is a C₃₋₃₀ alkyl group. In certain embodiments, in polymersof formulae II-b through II-d, R¹⁰⁰ is a C₃₋₁₀ alkyl group. In certainembodiments, in polymers of formulae II-b through II-d, R¹⁰⁰ is a C₃₋₆alkyl group. In certain embodiments, in polymers of formulae II-bthrough II-d, R¹⁰⁰ is a methyl group. In certain embodiments, inpolymers of formulae II-b through II-d, R¹⁰⁰ is an ethyl group. Incertain embodiments, in polymers of formulae II-b through II-d, R¹⁰⁰ isa random mixture of methyl and ethyl groups. In certain embodiments, inpolymers of formulae II-b through II-d, R¹⁰⁰ is a chloromethyl group. Incertain embodiments, in polymers of formulae II-b through II-d, R¹⁰⁰ isa random mixture of methyl and chloromethyl groups. In certainembodiments, in polymers of formulae II-b through II-d, R¹⁰⁰ is a randommixture of methyl and one or more C₃₋₃₀ alkyl groups. In certainembodiments, R¹⁰⁰ is partially absent, wherein one or more n-bracketedrepeating units comprise no R¹⁰⁰ group, while the remaining n-bracketingrepeating units comprise a R¹⁰⁰ group.

In certain embodiments, in polymers of formulae II-b through II-d, R¹⁰⁰is a —CH₂OR^(z) group. In certain embodiments, the CH₂OR^(z) groupcomprises an ether group (e.g. the polycarbonate chain is apoly(glycidyl ether carbonate)). In other embodiments the CH₂OR^(z)group comprises an ester group (e.g. the polycarbonate chain is apoly(glycidyl ester carbonate)). In certain embodiments, R¹⁰⁰ is arandom mixture of methyl and —CH₂OR^(z) groups.

In certain embodiments, the present invention encompasses polymercompositions comprising polymer chains of formulae II through II-d abovewherein the value of n is, on average, between about 5 and about 200. Incertain embodiments, the value of n is, on average between about 5 andabout 100. In certain embodiments, the value of n is, on average betweenabout 5 and about 50. In certain embodiments, the value of n is, onaverage between about 5 and about 25. In certain embodiments, the valueof n is, on average between about 10 and about 20. In certainembodiments, the value of n is, on average between about 5 and about 10.

In certain embodiments, the present invention encompasses polymercompositions comprising polymer chains of formulae II through II-d abovewherein the value of m is, on average, between about 4 and about 500. Incertain embodiments, the value of m is, on average between about 5 andabout 200. In certain embodiments, the value of m is, on average betweenabout 5 and about 50. In certain embodiments, the value of m is, onaverage between about 5 and about 25. In certain embodiments, the valueof m is, on average between about 10 and about 20. In certainembodiments, the value of n is, on average between about 5 and about 10.

In certain embodiments, where the polymer has one of the formulae II-cor II-d, and R¹⁰⁰ is present, the head to tail ratio of adjacent

groups is greater than about 80%. In certain embodiments, the head totail ratio is greater than about 90%. In certain embodiments, the headto tail ratio is greater than about 91%. In certain embodiments, thehead to tail ratio is greater than about 92%. In certain embodiments,the head to tail ratio is greater than about 93%. In certainembodiments, the head to tail ratio is greater than about 94%. Incertain embodiments, the head to tail ratio is greater than about 95%.

In certain embodiments, copolymers of formula A-L-B described above arecharacterized in that they have narrow polydispersity indices. In someembodiments, the PDIs of block copolymers of the present invention areless than about 2. In certain embodiments, the PDI is less than 1.5. Insome embodiments, the PDI is less than 1.4, less than 1.2 or less thanabout 1.1.

In certain embodiments, a polymer A-L-B is a block copolymer ofpolypropylene carbonate) (PPC) or a derivative thereof and poly(ethyleneglycol) (PEG) or a derivative thereof. In certain embodiments, suchPPC-PEG block copolymers have a formula selected from the groupconsisting of:

In certain embodiments, a polymer A-L-B is a block copolymer ofpoly(propylene carbonate) (PPC) or a derivative thereof andpoly(propylene glycol) (PPG) or a derivative thereof. In certainembodiments, such PPC-PPG block copolymers have a formula selected fromthe group consisting of:

In certain embodiments, a polymer A-L-B is a block copolymer ofpoly(propylene carbonate) (PPC) or a derivative thereof andpolyoxymethylene (POM) or a derivative thereof. In certain embodiments,such PPC-POM block copolymers have a formula selected from the groupconsisting of:

In certain embodiments, a polymer A-L-B is a block copolymer ofpoly(ethylene carbonate) (PEC) or a derivative thereof and poly(ethyleneglycol) (PEG) or a derivative thereof. In certain embodiments, suchPEC-PEG block copolymers have a formula selected from the groupconsisting of:

In certain embodiments, a polymer A-L-B is a block copolymer ofpoly(ethylene carbonate) (PEC) or a derivative thereof and polypropyleneglycol (PPG) or a derivative thereof. In certain embodiments, suchPEC-PPG block copolymers have a formula selected from the groupconsisting of:

In certain embodiments, a polymer A-L-B is a block copolymer ofpoly(ethylene carbonate) (PEC) or a derivative thereof andpolyoxymethylene (POM) or a derivative thereof. In certain embodiments,such PEC-POM block copolymers have a formula selected from the groupconsisting of:

In certain embodiments, a polymer A-L-B is a block copolymer of analiphatic polycarbonate (APC) and a polyether, wherein the APC comprisesa random copolymer such as those derived from copolymerization of two ormore different epoxides and carbon dioxide. In certain embodiments, suchblock copolymers comprise PEG (poly(ethylene glycol)), polypropyleneglycol), or polyoxymethylene.

In certain embodiments, APC-PEG block copolymers have a formula selectedfrom the group consisting of:

and, wherein R¹ is a mixture of two or more moieties selected from thegroup consisting of —H, methyl, ethyl, C₃₋₃₀ alkyl, CH₂Cl, CF₃, andCH₂OR^(z).

In certain embodiments, R¹ is a mixture of methyl and ethyl groups. Insome embodiments, R¹ is a mixture of —H and methyl groups. In certainembodiments, R¹ is a mixture of methyl groups and C₃₋₆ alkyl groups. Incertain embodiments, R¹ is a mixture of methyl groups and C₆₋₂₄ alkylgroups.

In certain embodiments, a polymer A-L-B is a block copolymer of analiphatic polycarbonate (APC) and poly(propylene glycol) (PPG) or aderivative thereof, wherein the APC comprises a random copolymer such asthose derived from copolymerization of two or more different epoxidesand carbon dioxide. In certain embodiments, such APC-PPG blockcopolymers have a formula selected from the group consisting of:

and, wherein

-   R¹ is a mixture of two or more moieties selected from the group    consisting of —H, methyl, ethyl, C₃₋₃₀ alkyl, CH₂Cl, CF₃, and    CH₂OR^(z). In certain embodiments, R¹ is a mixture of methyl and    ethyl groups. In other embodiments, R¹ is a mixture of —H and methyl    groups. In certain embodiments, R¹ is a mixture of methyl groups and    C₃₋₆ alkyl groups. In certain embodiments, R¹ is a mixture of methyl    groups and C₆₋₂₄ alkyl groups.

In certain embodiments, polymers of the present invention encompasstriblock copolymers having a hydrophilic central block flanked by twopolycarbonate chains. In certain embodiments, such triblock copolymershave the formula A-B-A, where each A is a polycarbonate orpolyethercarbonate chain having from about 3 to about 500 repeatingunits and -B- is a hydrophilic oligomer having from about 4 to about 200repeating units.

In certain embodiments, A-B-A triblock copolymers have the formula X:

-   where R^(a), R^(b), R^(c), R^(d), n, Z, and m are as defined above,    and where n′ is, on average approximately equal to n.

In certain embodiments, A-B-A triblock copolymers have the formula X-a:

where R^(z), R^(a), R^(b), R^(c), R^(d), n, m, and n′ are as definedabove.

In certain embodiments, A-B-A triblock copolymers have the formula X-b:

where R¹⁰⁰, n, n′, and m are as defined above.

In certain embodiments, A-B-A triblock copolymers have the formula X-c:

where R¹⁰⁰, n, n′, and m are as defined above.

In certain embodiments, A-B-A triblock copolymers have the formula X-d:

where R¹⁰⁰, n, n′, and m are as defined above.

In certain embodiments, A-B-A triblock copolymers have the formula X-e:

where R^(z), R¹⁰⁰, n, n′, and m are as defined above.

In certain embodiments, in polymers of formulae X-a or X-e, R^(z) isR¹⁰. In certain embodiments, in polymers of formulae X-a or X-e, R^(z)is an optionally substituted aliphatic group. In certain embodiments,R^(z) is selected from the group consisting of methyl, ethyl, n-propyl,i-propyl, n-butyl, sec-butyl, t-butyl, allyl and benzyl. In certainembodiments, in polymers of formulae X-a or X-e, R^(z) is an acyl group.In certain embodiments, R^(z) is selected from the group consisting offormate, acetate, trifluoroacetate, propionate, and optionallysubstituted benzoate. In certain embodiments, in polymers of formulaeX-a or X-e, R^(z) is —Si(R¹⁰)₃. In certain embodiments, in polymers offormulae X-a or X-e, R^(z) is a silyl group. In certain embodiments,R^(z) is selected from the group consisting of trimethylsilyl,triethylsilyl, triisopropyl silyl, t-butyldimethylsilyl, andt-butyldiphenylsilyl. In certain embodiments, in polymers of formulaeX-a or X-e, R^(z) is a sulfonate group.

In certain embodiments, in polymers of formulae X-b through X-e, R¹⁰⁰ isabsent (e.g. the polycarbonate chain comprises poly(ethylene carbonate).In certain embodiments, in polymers of formulae X-b through X-e, R¹⁰⁰ isa methyl group. In certain embodiments, in polymers of formulae X-bthrough X-e, R¹⁰⁰ is an ethyl group. In certain embodiments, in polymersof formulae X-b through X-e, R¹⁰⁰ is a random mixture of methyl andethyl groups. In certain embodiments, in polymers of formulae X-bthrough X-e, R¹⁰⁰ is a chloromethyl group. In certain embodiments, inpolymers of formulae X-b through X-e, R¹⁰⁰ is a random mixture of methyland chloromethyl groups. In certain embodiments, in polymers of formulaeX-b through X-e, R¹⁰⁰ is a random mixture of methyl and one or moreC₃₋₃₀ alkyl groups.

In certain embodiments, in polymers of formulae X-b through X-e, R¹⁰⁰ isa —CH₂OR^(z) group. In certain embodiments, the CH₂OR^(z) groupcomprises an ether group (e.g. the polycarbonate chain is apoly(glycidyl ether carbonate)). In some embodiments, the CH₂OR^(z)group comprises an ester group (e.g. the polycarbonate chain is apoly(glycidyl ester carbonate)). In certain embodiments, R¹⁰⁰ is arandom mixture of —H and —CH₂OR^(z) groups. In certain embodiments, R¹⁰⁰is a random mixture of C₁₋₄ alkyl groups and —CH₂OR^(z) groups. Incertain embodiments, R¹⁰⁰ is a random mixture of methyl and —CH₂OR^(z)groups.

In certain embodiments, provided polymer compositions comprise polymerchains of formulae X through X-e, wherein the value of n is, on average,between about 3 and about 200. In certain embodiments, the value of nis, on average between about 3 and about 100. In certain embodiments,the value of n is, on average between about 3 and about 50. In certainembodiments, the value of n is, on average between about 3 and about 25.In certain embodiments, the value of n is, on average between about 10and about 20. In certain embodiments, the value of n is, on averagebetween about 3 and about 10.

In certain embodiments, provided polymer compositions comprise polymerchains of formulae X through X-e above wherein the value of m is, onaverage, between about 4 and about 500. In certain embodiments, thevalue of m is, on average between about 5 and about 200. In certainembodiments, the value of m is, on average between about 5 and about 50.In certain embodiments, the value of m is, on average between about 5and about 25. In certain embodiments, the value of m is, on averagebetween about 10 and about 20. In certain embodiments, the value of nis, on average between about 5 and about 10.

In certain embodiments, where a provided polymer has one of the formulaeX-b through X-e, the head to tail ratio of adjacent

groups is greater than about 80%. In certain embodiments, the head totail ratio is greater than about 90%. In certain embodiments, the headto tail ratio is greater than about 92%. In certain embodiments, thehead to tail ratio is greater than about 95%.

In certain embodiments, provided A-B-A copolymers have narrowpolydisperisity indices. In some embodiments, the PDI of blockcopolymers of the present invention is less than about 2. In certainembodiments, the PDI is less than 1.5. In some embodiments, the PDI isless than 1.4, less than 1.2 or less than about 1.1.

In certain embodiments, triblock copolymers of the present inventioncomprise copolymers of poly(ethylene glycol) (PEG) or a derivativethereof and polypropylene carbonate) (PPC) or derivatives thereof. Incertain embodiments, these copolymers have a formula selected from thegroup consisting of:

In certain embodiments, provided triblock copolymers comprise copolymersof poly(ethylene glycol) (PEG) or a derivative thereof and poly(ethylenecarbonate) (PEC) or derivatives thereof. In certain embodiments, thesePEG-PEC triblock copolymers have a formula selected from the groupconsisting of:

In certain embodiments, provided triblock copolymers comprise copolymersof an aliphatic polycarbonate (APC) and poly(ethylene glycol) (PEG) or aderivative thereof, wherein an APC comprises a random copolymer such asthose derived from copolymerization of two or more different epoxidesand carbon dioxide. In certain embodiments, such APC-PEG triblockcopolymers have a formula selected from the group consisting of:

-   wherein R¹ is a mixture of two or more moieties selected from the    group consisting of —H, methyl, ethyl, C₃₋₃₀ alkyl, CH₂Cl, CF₃, and    CH₂OR^(z). In certain embodiments, R¹ is a mixture of methyl and    ethyl groups. In other embodiments, R¹ is a mixture of —H and methyl    groups. In certain embodiments, R¹ is a mixture of methyl groups and    C₃₋₆ alkyl groups. In certain embodiments, R¹ is a mixture of methyl    groups and C₆₋₂₄ alkyl groups.

In certain embodiments, provided triblock copolymers comprise copolymersof poly(propylene glycol) (PPG) or a derivative thereof andpoly(propylene carbonate) (PPC) or derivatives thereof. In certainembodiments, such copolymers have a formula selected from the groupconsisting of:

In certain embodiments, provided triblock copolymers comprise copolymersof polypropylene glycol) (PPG) or a derivative thereof and poly(ethylenecarbonate) (PEC) or derivatives thereof. In certain embodiments, thesePPG-PEC triblock copolymers have a formula selected from the groupconsisting of:

In certain embodiments, provided triblock copolymers comprise copolymersof an aliphatic polycarbonate (APC) and polypropylene glycol) (PPG) or aderivative thereof, wherein the APC comprises a random copolymer such asthose derived from copolymerization of two or more different epoxidesand carbon dioxide. In certain embodiments, such APC-PPG triblockcopolymers have a formula selected from the group consisting of:

wherein, R¹ is a mixture of two or more moieties selected from the groupconsisting of —H, methyl, ethyl, C₃₋₃₀ alkyl, CH₂Cl, CF₃, and CH₂OR^(z).In certain embodiments, R¹ is a mixture of methyl and ethyl groups. Inother embodiments, R¹ is a mixture of —H and methyl groups. In certainembodiments, R¹ is a mixture of methyl groups and C₃₋₆ alkyl groups. Incertain embodiments, R¹ is a mixture of methyl groups and C₆₋₂₄ alkylgroups.

In certain embodiments, provided triblock copolymers comprise copolymersof polyoxymethylene (POM) or a derivative thereof and poly(propylenecarbonate) (PPC) or derivatives thereof. In certain embodiments, suchcopolymers have a formula selected from the group consisting of:

In certain embodiments, provided triblock copolymers comprise copolymersof polyoxymethylene (POM) or a derivative thereof and poly(ethylenecarbonate) (PEC) or derivatives thereof. In certain embodiments, thesePOM-PEC triblock copolymers have a formula selected from the groupconsisting of:

In certain embodiments, provided triblock copolymers comprise copolymersof an aliphatic polycarbonate (APC) and polyoxymethylene (POM) or aderivative thereof, wherein an APC comprises a random copolymer such asthose derived from copolymerization of two or more different epoxidesand carbon dioxide. In certain embodiments, such APC-POM triblockcopolymers have a formula selected from the group consisting of:

wherein,

-   -   R¹ is a mixture of two or more moieties selected from the group        consisting of —H, methyl, ethyl, C₃₋₃₀ alkyl, CH₂Cl, CF₃, and        CH₂OR^(z). In certain embodiments, R¹ is a mixture of methyl and        ethyl groups. In other embodiments, R¹ is a mixture of —H and        methyl groups. In certain embodiments, R¹ is a mixture of methyl        groups and C₃₋₆ alkyl groups. In certain embodiments, R¹ is a        mixture of methyl groups and C₆₋₂₄ alkyl groups.

In certain embodiments, provided polymers are triblock copolymers havingan aliphatic polycarbonate central block flanked by two hydrophilicoligomers. In certain embodiments, such triblock copolymers have theformula B-A-B, where -A- is a polycarbonate or polyethercarbonate chainhaving from about 3 to about 500 repeating units and each B isindependently a hydrophilic oligomer having from about 4 to about 200repeating units.

In certain embodiments, such B-A-B triblock copolymers have the formulaXI:

-   where R^(a), R^(b), R^(c), R^(d), n, L, Z, Y, and m are as defined    above, and where m′ is, on average approximately equal to m.

In certain embodiments, B-A-B triblock copolymers have the formula XI-a:

where Y, Z, R^(a), R^(b), R^(c), R^(d), n, m, and m′ are as definedabove.

In certain embodiments, B-A-B triblock copolymers have the formula XI-b:

where Y, Z, R¹⁰⁰, n, m′, and m are as defined above.

In certain embodiments, B-A-B triblock copolymers have the formula XI-c:

where R¹⁰⁰, n, m′, and m are as defined above.

In certain embodiments, B-A-B triblock copolymers have the formula XI-d:

where R¹⁰⁰, n, m′, and m are as defined above.

In certain embodiments, in polymers of formulae XI through XI-b, Y is—H. In certain embodiments, in polymers of formulae XI through XI-b, Yis an optionally substituted aliphatic group. In certain embodiments, Yis selected from the group consisting of methyl, ethyl, n-propyl,i-propyl, n-butyl, sec-butyl, t-butyl, allyl and benzyl. In certainembodiments, in polymers of formulae XI through XI-b, Y is an acylgroup. In certain embodiments, Y is selected from the group consistingof formate, acetate, trifluoroacetate, propionate, and optionallysubstituted benzoate. In certain embodiments, in polymers of formulae XIthrough XI-b, Y is —Si(R¹⁰)₃. In certain embodiments, in polymers offormulae XI through XI-b, Y is a silyl group. In certain embodiments, Yis selected from the group consisting of trimethylsilyl, triethylsilyl,triisopropyl silyl, t-butyldimethylsilyl, and t-butyldiphenylsilyl. Incertain embodiments, in polymers of formulae XI through XI-b, Y is asulfonate group.

In certain embodiments, in polymers of formulae XI-b through XI-d, R¹⁰⁰is absent (e.g. the polycarbonate chain comprises poly(ethylenecarbonate). In certain embodiments, in polymers of formulae XI-b throughXI-d, R¹⁰⁰ is a methyl group. In certain embodiments, in polymers offormulae XI-b through XI-d, R¹⁰⁰ is an ethyl group. In certainembodiments, in polymers of formulae XI-b through XI-d, R¹⁰⁰ is a randommixture of methyl and ethyl groups. In certain embodiments, in polymersof formulae XI-b through XI-d, R¹⁰⁰ is a chloromethyl group. In certainembodiments, in polymers of formulae XI-b through XI-d, R¹⁰⁰ is a randommixture of methyl and chloromethyl groups. In certain embodiments, inpolymers of formulae XI-b through XI-d, R¹⁰⁰ is a random mixture ofmethyl and one or more C₃₋₃₀ alkyl groups.

In certain embodiments, in polymers of formulae XI-b through XI-d, R¹⁰⁰is a —CH₂OR^(z) group. In certain embodiments, a CH₂OR^(z) groupcomprises an ether group (e.g. the polycarbonate chain is apoly(glycidyl ether carbonate)). In some embodiments, a CH₂OR^(z) groupcomprises an ester group (e.g. the polycarbonate chain is apoly(glycidyl ester carbonate)). In certain embodiments, R¹⁰⁰ is arandom mixture of —H and —CH₂OR^(z) groups. In certain embodiments, R¹⁰⁰is a random mixture of C₁₋₄ alkyl groups and —CH₂OR^(z) groups. Incertain embodiments, R¹⁰⁰ is a random mixture of methyl and —CH₂OR^(z)groups.

In certain embodiments, provided polymer compositions comprise polymerchains of formulae XI through XI-d above wherein the value of n is, onaverage, between about 3 and about 200. In certain embodiments, thevalue of n is, on average between about 3 and about 100. In certainembodiments, the value of n is, on average between about 3 and about 50.In certain embodiments, the value of n is, on average between about 3and about 25. In certain embodiments, the value of n is, on averagebetween about 10 and about 20. In certain embodiments, the value of nis, on average between about 3 and about 10.

In certain embodiments, provided polymer compositions comprise polymerchains of formulae XI through XI-d above wherein the value of m is, onaverage, between about 4 and about 500. In certain embodiments, thevalue of m is, on average between about 5 and about 200. In certainembodiments, the value of m is, on average between about 5 and about 50.In certain embodiments, the value of m is, on average between about 5and about 25. In certain embodiments, the value of m is, on averagebetween about 10 and about 20. In certain embodiments, the value of nis, on average between about 5 and about 10.

In certain embodiments, where the polymer has one of the formulae XI-bthrough XI-d, R¹⁰⁰ is present, and the head to tail ratio of adjacent

groups is greater than about 80%. In certain embodiments, the head totail ratio is greater than about 90%. In certain embodiments, the headto tail ratio is greater than about 92%. In certain embodiments, thehead to tail ratio is greater than about 95%.

In certain embodiments, copolymers B-A-B have narrow polydisperisityindices. In some embodiments, the PDI of provided block copolymers isless than about 2. In certain embodiments, the PDI is less than 1.5. Insome embodiments, the PDI is less than 1.4, less than 1.2 or less thanabout 1.1.

In certain embodiments, for each of the formulae described herein, R¹⁰is optionally substituted C₁₋₂₀ aliphatic. In some embodiments, R¹⁰ isC₁₋₁₂ heteroaliphatic. In some embodiments, R¹⁰ is 6- to 14-memberedaryl. In some embodiments, R¹⁰ is 5- to 14-membered heteroaryl. In someembodiments, R¹⁰ is C₁₋₁₂ heteroaliphatic. In some embodiments, R¹⁰ ismethyl.

Polyether-Polycarbonates

In certain embodiments, provided copolymers are amphiphilic blockcopolymers wherein the carbonate-containing portion of the polymercomprises a polycarbonate containing both carbonate and ether linkages.In certain embodiments, a polymer A-L-B comprises a randompoly(ether-co-carbonate) and has the formula VI:

X, B, R^(a), R^(b), R^(c), R^(d), L, and n are as defined above.

It will be appreciated that in chemical formulae described herein, adashed line “

” means that the repeating unit on either side of the line occursrandomly throughout the polymer block contained within the parenthesesbetween which the dashed line appears.

In certain embodiments, a polymer A-L-B has the formula VI-a:

X, L, B, R¹⁰⁰, and n are as defined above.

In certain embodiments, a polymer A-L-B has the formula VII:

where X, L, R¹⁰⁰, n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VII-a:

where X, R¹⁰⁰, n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VII-b:

where X, n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VII-c:

where X, n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VII-d:

In certain embodiments, a polymer A-L-B has the formula VII-e:

In certain embodiments, a polymer A-L-B has the formula VII-f:

where n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VII-g:

In certain embodiments, a polymer A-L-B has the formula VII-h:

In certain embodiments, a polymer A-L-B has the formula VII-i:

where n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VII-j:

In certain embodiments, a polymer A-L-B has the formula VII-k:

In certain embodiments, a polymer A-L-B has the formula VIII:

where X, L, R¹⁰⁰, n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VIII-a:

where X, R¹⁰⁰, n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VIII-b:

where X, n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VIII-c:

where n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VIII-d:

In certain embodiments, a polymer A-L-B has the formula VIII-e:

In certain embodiments, a polymer A-L-B has the formula VIII-f:

where n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula VIII-g:

In certain embodiments, a polymer A-L-B has the formula VIII-h:

In certain embodiments, a polymer A-L-B has the formula IX:

where X, n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula IX-a:

where n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula IX-b:

In certain embodiments, a polymer A-L-B has the formula IX-c:

In certain embodiments, a polymer A-L-B has the formula IX-d:

where n and m are as defined above.

In certain embodiments, a polymer A-L-B has the formula IX-e:

In certain embodiments, a polymer A-L-B has the formula IX-f:

In certain embodiments, provided triblock copolymers have the formulaA-B-A wherein A is a polycarbonate chain containing both carbonate andether linkages has the formula (IX-g):

where R^(z), R¹⁰⁰, Z, n, n′ and m are as defined above.

As mentioned above, in some embodiments, provided copolymers have a highpercentage of carbonate linkages and a low percentage of ether linkages.In certain embodiments, for copolymers of formulae VI through IX-g, theproportion of ether linkages in the polyethercarbonate is less thanabout 50%. In certain embodiments, for copolymers of formulae VI throughIX-g, the proportion of ether linkages in the polyethercarbonate is lessthan about 46%. In certain embodiments, for copolymers of formulae VIthrough IX-g, the proportion of ether linkages in the polyethercarbonateis less than about 40%. In certain embodiments, for copolymers offormulae VI through IX-g, the proportion of ether linkages in thepolyethercarbonate is less than about 30%. In certain embodiments, forcopolymers of formulae VI through IX-g, the proportion of ether linkagesin the polyethercarbonate is less than about 20%. In certainembodiments, for copolymers of formulae VI through IX-g, the proportionof ether linkages in the polyethercarbonate is less than about 10%. Incertain embodiments, for copolymers of formulae VI through IX-g, theproportion of ether linkages in the polyethercarbonate is less thanabout 5%. In certain embodiments, for copolymers of formulae VI throughIX-g, the proportion of ether linkages in the polyethercarbonate is lessthan about 1%. In certain embodiments, for copolymers of formulae VIthrough IX-g, the proportion of ether linkages in the polyethercarbonateis less than about 0.1%.

In some embodiments, provided polymer compositions have an averagemolecular weight between 200 and 10,000 g/mol. In some embodiments,provided polymer compositions have an average molecular weight between200 and 5,000 g/mol. In some embodiments, provided polymer compositionshave an average molecular weight between 500 and 2,500 g/mol. In someembodiments, provided polymer compositions have an average molecularweight between 800 and 2,000 g/mol. In some embodiments, providedpolymer compositions have an average molecular weight between 500 and1,000 g/mol. In some embodiments, provided polymer compositions have anaverage molecular weight between 1,000 and 2,000 g/mol. In someembodiments, provided polymer compositions have an average molecularweight between 1,000 and 5,000 g/mol. In some embodiments, providedpolymer compositions have an average molecular weight between 200 and1,000 g/mol.

In certain embodiments, a block copolymer is provided in a quantity ofless than 5 weight % relative to the CO₂ phase. In certain embodiments,the block copolymer is provided in a quantity of less than 1 weight %.In certain embodiments, the block copolymer is provided in a quantity ofless than 0.5 weight %. In certain embodiments, the block copolymer isprovided in a quantity of less than 0.1 weight %. In certainembodiments, the block copolymer is provided in a quantity of less than0.05 weight %. In certain embodiments, the block copolymer is providedin a quantity of about 0.01 weight %.

In some embodiments, a provided copolymer composition has a solubilityin supercritical CO₂ of at least 0.01 weight % at a pressure of 4,000psi or higher. In some embodiments, a provided copolymer composition hasa solubility in supercritical CO₂ of at least 0.05 weight % at apressure of 4,000 psi or higher. In some embodiments, a providedcopolymer composition has a solubility in supercritical CO₂ of at least0.1 weight % at a pressure of 4,000 psi or higher. In some embodiments,a provided copolymer composition has a solubility in supercritical CO₂of at least 0.2 weight % at a pressure of 4,000 psi or higher. In someembodiments, a provided copolymer composition has a solubility insupercritical CO₂ of at least 0.5 weight % at a pressure of 4,000 psi orhigher. In some embodiments, a provided copolymer composition has asolubility in supercritical CO₂ of at least 1.0 weight % at a pressureof 4,000 psi or higher. In some embodiments, a provided copolymercomposition has a solubility in supercritical CO₂ of at least 0.01weight % at a pressure of 3,000 psi or higher. In some embodiments, aprovided copolymer composition has a solubility in supercritical CO₂ ofat least 0.05 weight % at a pressure of 3,000 psi or higher. In someembodiments, a provided copolymer composition has a solubility insupercritical CO₂ of at least 0.1 weight % at a pressure of 3,000 psi orhigher. In some embodiments, a provided copolymer composition has asolubility in supercritical CO₂ of at least 0.2 weight % at a pressureof 3,000 psi or higher. In some embodiments, a provided copolymercomposition has a solubility in supercritical CO₂ of at least 0.5 weight% at a pressure of 3,000 psi or higher. In some embodiments, a providedcopolymer composition has a solubility in supercritical CO₂ of at least1.0 weight % at a pressure of 3,000 psi or higher. In some embodiments,a provided copolymer composition has a solubility in supercritical CO₂of at least 0.01 weight % at a pressure of 2,000 psi or higher. In someembodiments, a provided copolymer composition has a solubility insupercritical CO₂ of at least 0.05 weight % at a pressure of 2,000 psior higher. In some embodiments, a provided copolymer composition has asolubility in supercritical CO₂ of at least 0.1 weight % at a pressureof 2,000 psi or higher. In some embodiments, a provided copolymercomposition has a solubility in supercritical CO₂ of at least 0.2 weight% at a pressure of 2,000 psi or higher. In some embodiments, a providedcopolymer composition has a solubility in supercritical CO₂ of at least0.5 weight % at a pressure of 2,000 psi or higher. In some embodiments,a provided copolymer composition has a solubility in supercritical CO₂of at least 1.0 weight % at a pressure of 2,000 psi or higher. In someembodiments, a provided copolymer composition has a solubility insupercritical CO₂ of at least 0.01 weight % at a pressure of 1,000 psior higher. In some embodiments, a provided copolymer composition has asolubility in supercritical CO₂ of at least 0.05 weight % at a pressureof 1,000 psi or higher. In some embodiments, a provided copolymercomposition has a solubility in supercritical CO₂ of at least 0.1 weight% at a pressure of 1,000 psi or higher. In some embodiments, a providedcopolymer composition has a solubility in supercritical CO₂ of at least0.2 weight % at a pressure of 1,000 psi or higher. In some embodiments,a provided copolymer composition has a solubility in supercritical CO₂of at least 0.5 weight % at a pressure of 1,000 psi or higher. In someembodiments, a provided copolymer composition has a solubility insupercritical CO₂ of at least 1.0 weight % at a pressure of 1,000 psi orhigher.

In some embodiments, provided copolymers form polymersomes. Having readthe present disclosure, one of ordinary skill in the art would be ableto carry out routine experimentation to form polymersomes from providedamphiphilic copolymers. Using methods well known to the skilled artisan,parameters such as polymer concentration, solvent, temperature, andvarious physical means (e.g., shearing, dialysis, etc.) can be appliedto achieve vesicle formation. Depending upon the desired use of thevesicle (e.g., drug delivery, viscosifying agent, etc.), the skilledartisan will select the appropriate copolymer to achieve the desiredpolymersome properties.

One of ordinary skill will also be familiar with a variety ofcharacterization techniques that can be used to determine the degree ofvesicle formation. For example, T_(m), scanning electron microscopy,transmission electron microscopy, dynamic stress rheometer, and dynamiclight scattering, to name but a few, are all routine techniques incharacterizing polymersome vesicles. Further guidance can be found inU.S. Pat. Appl. Publication 2005/0215438.

Certain polymers of the present invention can be produced bycopolymerization of carbon dioxide and epoxides using catalysts adaptedfrom those disclosed in US Pat. Nos. 6,870,004; and 7,304,172, inpending PCT application Nos. PCT/US09/56220, PCT/US09/54773, and inpublished PCT applications WO2008136591A1 and WO2008150033A1, theentirety of each of which is incorporated herein by reference.

In certain methods of the present invention, the methods includesynthesizing a polymer by reacting an epoxide and carbon dioxide in thepresence of a suitable catalyst and a polyether chain transfer agenthaving one free OH group as shown in Scheme 1:

The method of Scheme 1 is suitable for the synthesis of compoundsdescribed above wherein the polyether moiety is capped with a Y groupthat is not —H, and the polycarbonate chain is terminated with an OHgroup. Experimental conditions and methods suitable for this process aredescribed more fully in the Examples section below, and in co-pendingInternational Patent Application No. PCT/US2009/056220, filed Sep. 8,2009, the entire contents of which are hereby incorporated by reference.

The products of Scheme 1 can be further modified by reactions well knownto those skilled in the art of organic synthesis such as alkylation,acylation, sulfonation, or silylation to yield compounds wherein thepolycarbonate chain is capped with a non-OH end group. This is shown inScheme 2:

It will be appreciated that there are many possible variationsencompassed by the synthetic approaches detailed in Schemes 1-5,including the choice of suitable protecting (capping) chemistries forthe polymer termini. Suitable hydroxyl and carboxyl protecting groupsare well known in the art and include those described in detail inProtecting Groups in Organic Synthesis, T. W. Greene and P. G. M. Wuts,3^(rd) edition, John Wiley & Sons, 1999, the entirety of which isincorporated herein by reference.

For example, where it is desired that the polyether portion of suchpolymers have a free OH group, the polyether chain transfer agent ofScheme 1 can be chosen to contain on one terminus a labile group thatcan be removed after construction of the block co-polymer. Exemplaryapproaches include the use of mono-benzyl or mono-allyl polyetherstarting material followed by hydrogenolysis of the benzyl or allylether after construction of the copolymer. Another viable approach isthe use of a monosilylated polyether chain transfer agent followed byfluoride mediated cleavage of the silyl ether after construction of thecopolymer. It will be appreciated that numerous other hydroxylprotecting groups that can be cleaved under relatively mild conditionsare known in the art and can be used to similar effect in accordancewith the present disclosure.

In certain embodiments, it is desirable to have a free —OH group on thehydrophilic polyether portion of the block co-polymer and a non-OHend-group on the polycarbonate. Polymers of this type can be producedusing the methods just described by capping the —OH group of thepolycarbonate as described above and shown in Scheme 2, followed byremoval of a suitably chosen protecting group on the polyether block ofthe copolymer as just described.

For block copolymers comprising polycarbonates derived frommonosubstituted epoxides, it will be appreciated that there aredifferent regiochemical arrangements possible for the orientation of thepolycarbonate chain relative to the polyether. For example, the twocompounds shown below are both block co-polymers of PEG andpolypropylene carbonate):

Compound (A) is typical of the product formed using the method shown inScheme 1, where the epoxide is propylene oxide. The directionality ofthe epoxide enchainment during the polymerization will be predominately(>60%) from the less hindered ring carbon, therefore the last enchainedepoxide which comprises the chain terminus at the end of synthesis willbe oriented predominately as shown in the first structure. If one uses acomplementary approach described below in Scheme 5, wherein a preformedmonofunctional polycarbonate chain is ligated to a polyether chain, theregiochemistry will be predominantly as shown in structure (B) since amono-hydroxy terminated polypropylene carbonate) chain resulting frominitiation by a moiety X, will have predominately secondary OH groups atthe reactive terminus. Reaction of these OH groups to ligate or initiatea polyether chain will result predominantly (e.g. >60%) in theregiochemistry shown in compound (B). It will be appreciated that thisphenomenon is observed also with the use of other epoxide substratessuch as butylene oxide, epichlorohydrin, and glycidol derivatives, butnot with unsubstituted, or symmetrically substituted epoxides such asethylene oxide or 2-butene oxide.

In certain embodiments of the present invention, the methods includesynthesizing a triblock copolymer by reacting an epoxide and carbondioxide in the presence of a suitable catalyst and a polyether chaintransfer agent having two free OH group as shown in Scheme 3. Compoundsof formulae X through X-d described above can be made according to thismethod.

As shown in scheme 4, the products of Scheme 3, can be end-capped asdescribed above for diblock co-polymers.

It will be appreciated that these methods can also be applied usingother —OH or CO₂H terminated oligomers as chain transfer agents in placeof the polyethers depicted above. For example, polyesters,polyacrylates, or propoxylated or ethoxylated derivatives thereof can beused as well.

In some embodiments, the present disclosure encompasses methods ofmaking amphiphilic polymers as described hereinabove comprising the stepof synthesizing a polycarbonate chain having one end terminated with an—OH group, followed by ligation to a polyether. Such ligation may beaccomplished by forming an ether bond to a preformed polyether moleculeor, more preferably, by conducting a second polymerization in thepresence of a suitable polyether precursor such as an epoxide orformaldehyde to synthesize the polyether block directly onto theco-polymer. This approach is outlined in Scheme 5.

It will be appreciated that this approach leads to compounds having an—OH terminal group on the polyether block and a non-OH group derivedfrom the polycarbonate chain initiator at the polycarbonate terminus ofthe polymer.

Similarly, triblock co-polymers derived from ether synthesis upon adi-hydroxy terminated polycarbonate are also possible, this process willyield compounds of formula XI-b described hereinabove.

For block co-polymers made by polymerizing a polyether precursor onto apreformed polycarbonate, it should be noted that the resulting compoundsmay contain a linker between the polycarbonate and the polyethercorresponding to a ring-opened molecule of the epoxide from which thepolycarbonate was formed. This is shown in structure (C) below for apolycarbonate-co-polyethylene glycol where the linker is denoted “L” andin other similar examples hereinabove.

Of course, in cases where the epoxide subunit of the polycarbonatecorresponds to the repeat unit of a polyether block (i.e. poly(ethylenecarbonate)-block-poly(ethylene glycol)), such a linker moiety will notbe distinguishable and the linker 1′ can be regarded as comprising asingle covalent bond.

In some embodiments, the present invention encompasses methods for theformation of emulsions between supercritical carbon dioxide and a polarliquid. In certain embodiments, the polar liquid comprises water or anaqueous solution. In certain embodiments, the method includes the stepof agitating a biphasic mixture of supercritical CO₂ and the polarliquid in the presence of any one or more of the block copolymersdescribed hereinabove. In another embodiment, the method of forming theemulsion comprises forcing a mixture of the two phases and thesurfactant through a porous substance.

In certain embodiments, the present invention provides a method offorming an emulsion of supercritical CO₂ and an aqueous phase, themethod comprising a step of agitating supercritical CO₂ and the aqueousphase in the presence of a block copolymer having a formula:

-   -   X is selected from the group consisting of: halogen; —OH; azide,        nitrile, and —OR^(z);    -   each R^(a), R^(b), R^(c), and R^(d) is independently selected        from the group consisting of: hydrogen, halogen, —CH₂OR^(z),        optionally substituted C₁₋₁₀ aliphatic, optionally substituted        6- to 14-membered aromatic, optionally substituted 3- to        14-membered heterocyclic, and optionally substituted 5- to        14-membered heteroaryl, and where any two or more of R^(a),        R^(b), R^(c), and R^(d) may be taken together to form an        optionally substituted 3- to 12-membered ring, optionally        containing one or more heteroatoms;    -   L is a bond or a polyfunctional moiety,    -   B is a hydrophilic oligomer having from about 4 to about 100        repeating units,    -   n is an integer between 4 and 100,    -   R^(z) is selected from the group consisting of —C(O)R¹⁰,        —SO₂R¹⁰, —Si(R¹⁰)₃, —C(O)N(R¹⁰)₂, optionally substituted C₁₋₁₂        aliphatic; optionally substituted C₁₋₁₂ heteroaliphatic;        optionally substituted 6- to 14-membered aryl; and optionally        substituted 5- to 14-membered heteroaryl, and        -   R¹⁰ is an optionally substituted moiety selected from the            group consisting of: C₁₋₂₀ aliphatic; C₁₋₁₂ heteroaliphatic;            6- to 14-membered aryl; and 5- to 14-membered heteroaryl.

In certain embodiments, the present invention provides a method offorming an emulsion of supercritical CO₂ and an aqueous phase, themethod comprising a step of agitating supercritical CO₂ and the aqueousphase in the presence of a block copolymer having a formula:

wherein

-   -   X′ is selected from the group consisting of —OH, and —OR^(z),        R¹⁰⁰ is optionally present, and if present is selected from the        group consisting of —CH₃, —CF₃, —CH₂CH₃, —CH₂OR^(z), and —CH₂Cl,    -   each n is independently an integer between 4 and 100,    -   —Z— is an optionally substituted C₁₋₆ aliphatic group,    -   m is an integer between 5 and 200,    -   R^(z) is selected from the group consisting of —C(O)R¹⁰,        —SO₂R¹⁰, —Si(R¹⁰)₃, —C(O)N(R¹⁰)₂, optionally substituted C₁₋₁₂        aliphatic; optionally substituted C₁₋₁₂ heteroaliphatic;        optionally substituted 6- to 14-membered aryl; and optionally        substituted 5- to 14-membered heteroaryl, and    -   R¹⁰ is at each occurrence an optionally substituted moiety        independently selected from the group consisting of: C₁₋₁₂        aliphatic; C₁₋₁₂ heteroaliphatic; 6- to 14-membered aryl; and 5-        to 14-membered heteroaryl.

In certain embodiments, provided block co-polymers useful for forming anemulsion are of the formula:

-   -   R¹⁰⁰ is optionally present, and if present is selected from the        group consisting of —CH₃, —CF₃, —CH₂CH₃, —CH₂OR^(z), —CH₂Cl, a        C₆₋₃₀ alkyl group, and mixtures of any two or more of these.

In certain embodiments, the block copolymers and methods describedhereinabove have utility in modifying the viscosity of supercritical CO₂water mixtures. Such viscosity modifying properties can have utility inthe use of supercritical CO₂ as a fluid for secondary or tertiaryrecovery of product from oil wells. Methods of using and means ofmodeling compounds for such applications are described in published PCTapplication WO 2000035998 A2 which is incorporated herein by referenceand in references cited therein.

In some embodiments, the present invention provides a method ofmodifying the viscosity of a fluid comprising a mixture of supercriticalCO₂ and water, the method comprising a step of agitating the mixture inthe presence of a block copolymer having a formula:

-   -   X is selected from the group consisting of: halogen; —OH; azide,        nitrile, and —OR^(z);    -   each R^(a), R^(b), R^(c), and R^(d) is independently selected        from the group consisting of: hydrogen, halogen, —CH₂OR^(z),        optionally substituted C₁₋₁₀ aliphatic, optionally substituted        6- to 14-membered aromatic, optionally substituted 3- to        14-membered heterocyclic, and optionally substituted 5- to        14-membered heteroaryl, and where any two or more of R^(a),        R^(b), R^(c), and R^(d) may be taken together to form an        optionally substituted 3- to 12-membered ring, optionally        containing one or more heteroatoms;    -   L is a bond or a polyfunctional moiety,    -   B is a hydrophilic oligomer having from about 4 to about 100        repeating units,    -   n is an integer between 4 and 100,    -   R^(z) is selected from the group consisting of —C(O)R¹⁰,        —SO₂R¹⁰, —Si(R¹⁰)₃, —C(O)N(R¹⁰)₂, optionally substituted C₁₋₁₂        aliphatic; optionally substituted C₁₋₁₂ heteroaliphatic;        optionally substituted 6- to 14-membered aryl; and optionally        substituted 5- to 14-membered heteroaryl, and    -   R¹⁰ is an optionally substituted moiety selected from the group        consisting of: C₁₋₂₀ aliphatic; C₁₋₁₂ heteroaliphatic; 6- to        14-membered aryl; and 5- to 14-membered heteroaryl.

In certain embodiments, the present invention provides a method ofmodifying the viscosity of a fluid comprising a mixture of supercriticalCO₂ and water, the method comprising a step of agitating the mixture inthe presence of a block copolymer having a

wherein

-   -   X′ is selected from the group consisting of —OH, and —OR^(z)    -   R¹⁰⁰ is optionally present, and if present is selected from the        group consisting of —CH₃, —CF₃, —CH₂CH₃, —CH₂OR^(z), and —CH₂Cl;    -   each n is independently an integer between 4 and 100,    -   —Z— is an optionally substituted C₁₋₆ aliphatic group,    -   m is an integer between 5 and 200,    -   R^(z) is selected from the group consisting of —C(O)R¹⁰,        —SO₂R¹⁰, —Si(R¹⁰)₃, —C(O)N(R¹⁰)₂, optionally substituted C₁₋₁₂        aliphatic; optionally substituted C₁₋₁₂ heteroaliphatic;        optionally substituted 6- to 14-membered aryl; and optionally        substituted 5- to 14-membered heteroaryl, and    -   R¹⁰ is at each occurrence an optionally substituted moiety        independently selected from the group consisting of: C₁₋₁₂        aliphatic; C₁₋₁₂ heteroaliphatic; 6- to 14-membered aryl; and 5-        to 14-membered heteroaryl.

In certain embodiments of the methods described above, a block copolymeris provided as a solution in supercritical CO₂.

In certain embodiments, the present invention includes methods ofenhancing product recovery from oil wells by introducing any of theabove-described polymers to an oil-containing geological formation. Insome embodiments, such methods comprise the step of pumping a providedcopolymer into an oil well. In certain embodiments, the polymers areintroduced in combination with supercritical CO₂. In certain methods,the supercritical CO₂ is combined with water or brine to form anemulsion capable of flushing trapped oil from geological formations.

EXAMPLES Example 1 Synthesis of Poly(propylenecarbonate)-block-poly(ethylene glycol) methyl ether 1

(a compound of formula II-d wherein X′ is OH, R¹⁰⁰ is —CH₃, L is a bond,and Z is —CH₂CH₂— and Y′ is CH₃ with n being approximately 11 and mbeing approximately 11)

Procedure A:

A 3 oz. Fischer-Porter bottle was fitted with a pressure head andmagnetic stirrer. The reaction vessel was dried in vacuo using a heatgun and cooled to rt. catalyst C-I (24 mg, 3.6×10⁻⁵ mol) andbis(triphenylphosphine)iminium chloride (21 mg, 3.6×10⁻⁵ mol) werecharged to the reaction vessel. The vessel was evacuated for 15 min,then backfilled with nitrogen. This procedure was repeated twice more.While under the positive flow of nitrogen, propylene oxide (20 mL, 0.29mol) and poly(ethylene glycol) methyl ether (M_(n)=550 g/mol, 2.2 mL,7.1×10⁻³ mol) were charged to the reaction vessel. The reaction wasplaced into a 30° C. water bath, stirred, and pressurized with carbondioxide (100 psi).

After 21.5 h the reaction was vented and quenched with a methanolicsolution (3 mL) of tosic acid (14 mg, 7.2×10⁻⁵ mol). The reaction wasstirred for 10 min at rt and the unreacted propylene oxide was removedby evaporation. The resulting polymer was diluted with acetone (10 mL)and filtered through filter paper to remove solids. The filtrate wasshaken with Dowex MSC (H) (5.0 g) for 2 h and filtered through a finemesh. The filtrate was concentrated, in vacuo, to produce 1.0 g (4%yield) of a tan, slightly viscous polymer (M_(w)=1,688 g/mol,M_(w)/M_(n)=1.06; T_(d(onset))=210° C., containing 24% propylenecarbonate).

Procedure B:

A 300 mL stainless steel reactor was dried, in vacuo, using a hot plate(120° C.) and cooled to rt. catalyst C-I (60 mg, 8.9×10⁻⁵ mol) andbis(triphenylphosphine)iminium chloride (51 mg, 8.9×10⁻⁵ mol) werecharged to the reaction vessel. The vessel was evacuated for 15 min,then backfilled with nitrogen. This procedure was repeated twice more.

While under the positive flow of nitrogen, propylene oxide (50 mL, 0.71mol) and poly(ethylene glycol) monomethylether (M_(n)=550 g/mol, 4.5 mL,8.9×10⁻³ mol) were charged to the reaction vessel. The reaction waspressurized to 300 psi of carbon dioxide and heated to 30° C. using aheating mantle.

After 16 h the reaction was vented and quenched with a methanolicsolution (3 mL) of tosic acid (approx. 34 mg, 1.8×10⁻⁴ mol). Thereaction was stirred for 10 min at rt and the unreacted propylene oxidewas removed by evaporation. The resulting polymer samples were dilutedwith acetone (100 mL) and filtered through filter paper to removesolids. The filtrate was shaken with Dowex MSC (H) (9.0 g) for 2 h andfiltered through a fine mesh. The filtrate was concentrated, in vacuo,to produce a total of 11.5 g (16% yield) of a tan viscous polymer(M_(w)=3,057 g/mol, M_(w)/M_(n)=1.06; T_(g)=−34° C.; T_(d(onset))=252°C., 7% propylene carbonate).

Example 2 Synthesis of Poly(propylene carbonate)-block-poly(propyleneglycol)monobutyl ether (2)

(a compound of formula II-d wherein X′ is OH, R¹⁰⁰ is —CH₃, L is a bond,and Z is —CH(CH₃)CH₂— and Y′ is n-butyl with n being approximately 5 andm being approximately 19)

Procedure A for 1 was followed except poly(propylene glycol) monobutylether (M_(n)=340 g/mol, 2.4 mL, 7.1×10⁻³ mol) was used as a chaintransfer agent. This produced 1.6 g (7% yield) of a yellow viscouspolymer (M_(w)=2,258 g/mol, M_(w)/M_(n)=1.08; T_(g)=−47° C.;T_(d(onset))=229° C., containing 15% propylene carbonate).

Example 3 Synthesis of poly(propylene carbonate)-block-poly(ethyleneglycol)-block-poly(propylene carbonate) (3)

(compounds of formula X-b where R¹⁰⁰ is methyl).

A 300 mL stainless steel reactor was dried, in vacuo, using a hot plate(120° C.) and cooled to rt. Catalyst C-I (182 mg, 2.7×10⁻⁴ mol) andBis(triphenylphosphine)iminium chloride (154 mg, 2.7×10⁻⁴ mol) werecharged to the reaction vessel. The vessel was evacuated for 15 min,then backfilled with nitrogen. This procedure was repeated twice more.While under the positive flow of nitrogen, propylene oxide (150 mL, 2.2mol) and poly(ethylene glycol) (M_(n)=400 g/mol, 9.5 mL, 2.7×10⁻² mol)were charged to the reaction vessel. The reaction was pressurized to 300psi of carbon dioxide and heated to 30° C. using a heating mantle.

At 2, 4, 6, and 8 h, 10 mL samples were removed from the reaction andquenched with a methanolic solution (3 mL) of tosic acid (7 mg, 3.9×10⁻⁵mol). After 26 h the reaction was vented and quenched with a methanolicsolution (3 mL) of tosic acid (54 mg, 3.0×10⁻⁴ mol). The reaction wasstirred for 10 min at rt and the unreacted propylene oxide was removedby evaporation. The resulting polymer samples were diluted with acetone(10 mL) and filtered through filter paper to remove solids. Thefiltrates were shaken with Dowex MSC (H) (5.0 g) for 2 h and filteredthrough a fine mesh. Each filtrate was concentrated, in vacuo, toproduce a total of 66.0 g (30% yield) of a tan, slightly viscouspolymer. 2 h sample (M_(w)=1,134 g/mol, M_(w)/M_(n)=1.14); 4 h sample(M_(w)=1,543 g/mol, M_(w)/M_(n)=1.07; T_(g)=−66° C.; T_(d(onset))=257°C.); 6 h sample (M_(w)=2,004 g/mol, M_(w)/M_(n)=1.06); 8 h sample(M_(w)=2,422 g/mol, M_(w)/M_(n)=1.04; T_(g)=−49° C.; T_(d(onset))=248°C., 6% propylene carbonate); 26 h sample (M_(w)=5,423 g/mol,M_(w)/M_(n)=1.02).

Example 4 Synthesis of polypropylenecarbonate)-acetate-block-poly(ethylene glycol) (4)

(a compound of formula II-c wherein X′ is -OAc, R¹⁰⁰ is —CH₃, L is abond, and Z is —CH₂CH₂— and Y′ is —H)

A 3 oz. Fischer-Porter bottle is fitted with a pressure head andmagnetic stirrer. The reaction vessel is dried in vacuo using a heat gunand cooled to rt. Catalyst C-I (24 mg, 3.6×10⁻⁵ mol) andbis(triphenylphosphine)iminium chloride (21 mg, 3.6×10⁻⁵ mol) arecharged to the reaction vessel. The vessel is evacuated for 15 min, thenbackfilled with nitrogen. While under a positive flow of nitrogen,propylene oxide (20 mL, 0.29 mol) and poly(ethylene glycol) monot-butyldimethylsilyl ether (7.1×10⁻³ mol prepared as described inJournal of Organic Chemistry (1991), 56(13), 4326-4329) are charged tothe reaction vessel. The reaction is placed into a 30° C. water bath,stirred, and pressurized with carbon dioxide (100 psi).

After 24 h the reaction is vented and quenched with a methanolicsolution (3 mL) of tosic acid (14 mg, 7.2×10⁻⁵ mol). The mixture isstirred for 10 min at rt and the unreacted propylene oxide is removed byevaporation. The resulting polymer is diluted with acetone (10 mL) andfiltered through filter paper to remove solids. The filtrate is shakenwith Dowex MSC (H) (5.0 g) for 2 h and filtered through a fine mesh. Thefiltrate is concentrated, in vacuo, to produce polymer 4a. This polymeris dissolved in dichloromethane (10 mL) containing triethyl amine (1 mL)and treated with acetic anhydride (0.5 mL). The mixture is heated toreflux for 16 h, then cooled to rt, diluted with dichloromethane (40 mL)and washed with water and then brine. The dichloromethane solution isdried on anhydrous K₂CO₃ and concentrated to give compound 4b. Polymer4b is dissolved in THF (20 mL) in a PTFE container andtetrabutylammonium fluoride (0.2 g) is added. The mixture is stirred for1 h, then poured into water and extracted with dichloromethane (5×20mL). The combined dichloromethane extracts are dried on K₂CO₃, filteredand concentrated to afford polymer 4.

Example 5 Synthesis of Poly(propylenecarbonate)-pivalate-block-poly(propylene glycol) (5)

(a compound of formula II-d wherein X′ is pivaloyl, R¹⁰⁰ is —CH₃, L is abond, Z is —CH(CH₃)CH₂— and Y′ is —H)

Compound 5 is synthesized under conditions similar to those described inExample 4, except mono-TMS-protected polypropylene glycol is used as thestarting material, and pivaloyl chloride is substituted for aceticanhydride.

Example 7 Synthesis of polypropylenecarbonate)-acetate-block-poly(ethylene glycol) (7)

(a compound of formula II-c wherein X is —OAc, R¹⁰⁰ is —CH₃, L is—CH₂CH(CH₃)O—, and Z is —CH₂CH₂—)

In a glovebox, catalyst C-II (5.4 mg) and PPN-acetate (4.8 mg) arecharged to an oven-dried 20 mL glass liner. The liner is inserted into astainless steel high pressure reactor. The system is purged with N₂ fivetimes and purged with CO₂ twice. While under the positive flow of CO₂,propylene oxide (5 mL) and acetic acid (200 μL) are charged to thereaction vessel. The reaction is heated to 50° C., then pressurized withcarbon dioxide (300 psi) and stirred. After 6 h the reaction is ventedand quenched with acidic methanol (0.2 mL). The reaction is cooled toroom temperature, and the resulting polymer is diluted with acetone (5mL) and transferred to a foil pan. The unreacted propylene oxide andacetone are removed by evaporation to produce polymer 7a as an oil.

In a dry 100 ml flask, 1 g of polymer 7a is dissolved in 15 mL ofdichloromethane. To this mixture is added 2 g of ethylene oxide followedby 150 mg of catalyst C-III dissolved in 5 mL of dichloromethane. Thismixture is stirred at rt for 48 h, then quenched by addition of a largeexcess of methanol. The volatile components are then removed undervacuum, the residue is dissolved in THF (100 mL) and filtered through a0.22 μm filter. Evaporation of the filtrate provides polymer 7 as aviscous oil.

Example 8 Synthesis of isopropyl ether capped poly(propylenecarbonate)-block-poly(propylene glycol) (8)

(a compound of formula II-c wherein X is —O-i-Pr, R¹⁰⁰ is —CH₃, L is abond, and Z is —CH₂CH(CH₃)—)

In a glovebox, catalyst C-II (50 mg) and PPN-chloride (48 mg) arecharged to an oven-dried 200 mL high pressure reactor. The reactor ispurged with N₂ five times and purged with CO₂ twice. While under thepositive flow of CO₂, propylene oxide (70 mL) and isopropyl alcohol (0.5mL) are charged to the reaction vessel. The reaction is heated to 35°C., then pressurized with carbon dioxide (300 psi) and stirred. After 6h the reaction is vented and quenched with acidic methanol (5 mL). Thereaction is cooled to room temperature, and the resulting polymer isdiluted with acetone (50 mL) and transferred to a pan. The unreactedpropylene oxide and acetone are removed by evaporation to providepolymer 8a as a viscous oil.

A 100 mL reactor is charged with polymer 8a (10 g) and zinchexacyanocobaltate catalyst (0.02 g). The mixture is stirred and heatedto 105° C., and is stripped under vacuum to remove traces of water frompolymer 8a. Ethylene oxide (2-3 g) is added in one portion. The reactorpressure is then monitored carefully. Additional ethylene oxide is notadded until an accelerated pressure drop occurs in the reactorindicating that the catalyst has become activated. When catalystactivation is verified, the remaining ethylene oxide (20 g) is addedgradually to keep the reactor pressure at about 10 psig. After ethyleneoxide addition is complete, the mixture is held at 105° C. until aconstant pressure is observed. Residual unreacted monomer is thenstripped under vacuum from the product, and the residue is cooled andrecovered to provide polymer 8 as a viscous oil.

Example 9 Synthesis of block-poly(ethylene glycol)-block polypropylenecarbonate)-block-poly(ethylene glycol) (9)

(a compound of formula XI-b wherein Y is H, Z is —CH₂CH₂, and —R¹⁰⁰ is—CH₃)

In a glovebox, catalyst C-I (5.4 mg) and PPN-chloride (4.8 mg) arecharged to an oven-dried 20 mL glass liner. The liner is inserted into astainless steel high pressure reactor. The system is purged with N₂ fivetimes and purged with CO₂ twice. While under the positive flow of CO₂,propylene oxide (5 mL) and propylene glycol (200 μL) are charged to thereaction vessel. The reaction is heated to 35° C., then pressurized withcarbon dioxide (300 psi) and stirred. After 6 h the reaction is ventedand quenched with acidic methanol (0.2 mL). The reaction is cooled toroom temperature, and the resulting polymer is diluted with acetone (5mL) and transferred to a foil pan. The unreacted propylene oxide andacetone are removed by evaporation to produce polymer 9a as a viscousoil.

In a dry flask, 1 g of polymer 9a and 5 mg of zinc hexacyanocobaltatecatalyst are combined. To this mixture is added 2 g of ethylene oxide.This mixture is stirred at rt for 48 h, then heated to 105° C. for 1 h.Residual unreacted monomer is then stripped under vacuum from theproduct, and the residue is cooled and recovered to provide polymer 9 asa viscous oil.

Supercritical Carbon Dioxide Solubility Tests:

Samples were evaluated for supercritical CO₂ (sc-CO₂) solubility at arange of pressures and concentrations using the apparatus and conditionsdescribed in the Journal of Supercritical Fluids 34 (2005), pp. 11-16,and Journal of Physical Chemistry 100 (1996) which are incorporatedherein by reference.

The solubility of the polymers of Examples 1-3 and related compounds insupercritical CO₂ and various concentrations, temperatures, andpressures are shown in FIGS. 1-4.

Emulsion Tests:

Samples were evaluated for the ability to stabilize foams betweensupercritical CO₂ (sc-CO₂) and water. Foam test conditions used awindowed cell containing equal volumes of liquid sc-CO₂ and brine orwater. The mixtures were agitated in the presence of 0.1 wt % surfactant(based on mass of CO₂) and the stability of the foam was observedvisually by periodically measuring the height of foam present in the CO₂phase and the depth of foam present in the aqueous phase. Plots of thesedata for the polymer compositions of examples 1-3 and related materialsare shown in FIGS. 4 and 5.

Further detail on suitable experimental conditions for thesemeasurements are found in Fluid Phase Equilibria (2003), 211(2), pp211-217 and in Chemistry of Materials (2002), 14(10), pp 4273-4280 whichare both incorporated herein by reference.

OTHER EMBODIMENTS

The foregoing has been a description of certain non-limiting embodimentsof the invention. Accordingly, it is to be understood that theembodiments of the invention herein described are merely illustrative ofthe application of the principles of the invention. Reference herein todetails of the illustrated embodiments is not intended to limit thescope of the claims, which themselves recite those features regarded asessential to the invention.

What is claimed is:
 1. A method for the synthesis of a block copolymerhaving a formula:

the method comprising the step of reacting an epoxide of formula

with carbon dioxide in the presence of a suitable catalyst and apolyether chain transfer agent having one free OH group; where X′ isselected from the group consisting of —OH and —OR^(z); each R^(a),R^(b), R^(c), and R^(d) is independently selected from the groupconsisting of hydrogen, halogen, —CH₂OR^(z), optionally substitutedC₁₋₁₀ aliphatic, optionally substituted 6- to 14-membered aromatic,optionally substituted 3- to 14-membered heterocyclic, and optionallysubstituted 5- to 14-membered heteroaryl, and where any two or more ofR^(a), R^(b), R^(c), and R^(d) may be taken together to form anoptionally substituted 3- to 12-membered ring, optionally containing oneor more heteroatoms; R^(z) is selected from the group consisting of R¹⁰,—C(O)R¹⁰, —SO₂R¹⁰, —Si(R¹⁰)₃, —C(O)N(R¹⁰)₂, or a hydroxyl protectinggroup; R¹⁰ is an optionally substituted moiety selected from the groupconsisting of C₁₋₂₀ aliphatic; C₁₋₁₂ heteroaliphatic; 6- to 14-memberedaryl; and 5- to 14-membered heteroaryl; —Z— is an optionally substitutedC₁₋₆ aliphatic group; —Y is selected from the group consisting of —H andR^(z); n is an integer between 4 and 100; and m is an integer between 5and
 200. 2. The method of claim 1, wherein the block copolymer has theformula:

wherein L is a bond or a polyfunctional moiety; and the epoxide has theformula:

wherein R¹⁰⁰ is optionally present and if present is selected from thegroup consisting of —CH₃, —CF₃, —CH₂CH₃, —CH₂OR^(z), and —CH₂Cl.
 3. Themethod of claim 2, wherein R¹⁰⁰ is absent.
 4. The method of claim 2,wherein R¹⁰⁰ is present.
 5. The method of claim 4, wherein the blockcopolymer has the formula:


6. The method of claim 4, wherein R¹⁰⁰ is a methyl group.
 7. The methodof claim 4, wherein R¹⁰⁰ is a random mixture of methyl groups and one ormore moieties selected from group consisting of ethyl, trifluoromethyl,chloromethyl, —CH₂OR^(z), and a C₆₋₃₀ alkyl group.
 8. The method ofclaim 1, wherein X′ is —OH.
 9. The method of claim 1, wherein X′ is—OR^(z).
 10. The method of claim 9, wherein a block copolymer formed bythe step of reacting the epoxide with carbon dioxide and a polyetherchain transfer agent is further modified by a reaction to convert —X′from an —OH group to an —OR^(z) group.
 11. The method of claim 10,wherein the block copolymer is modified by a reaction chosen from thegroup consisting of alkylation, acylation, sulfonation, or silylation.12. The method of claim 1, wherein —Z— is —CH₂CH₂—.
 13. The method ofclaim 1, wherein —Z— is —CH(CH₃)CH₂—.
 14. The method of claim 1, wherein—Z— is —CH₂—.
 15. The method of claim 1, wherein —Y is —H.
 16. Themethod of claim 1, wherein —Y is a C₁₋₆ aliphatic group.
 17. The methodof claim 1, wherein —Y is a hydroxyl protecting group.
 18. The method ofclaim 17, further comprising the step of treating the block copolymer toconvert the hydroxyl protecting group to a free hydroxyl group.
 19. Themethod of claim 18, wherein the hydroxyl protecting group is selectedfrom the group consisting of an allyl ether and benzyl ether.
 20. Themethod of claim 19, wherein the step of converting the hydroxylprotecting group to a free hydroxyl group comprises hydrogenolysis. 21.The method of claim 18, wherein the hydroxyl protecting group comprisesa silyl ether.
 22. A method for the synthesis of a block copolymerhaving a formula:

the method comprising the step of reacting an epoxide of formula

with carbon dioxide in the presence of a suitable catalyst and a chaintransfer agent having a formula:B-L-OH where X′ is selected from the group consisting of —OH and—OR^(z); each R^(a), R^(b), R^(c), and R^(d) is independently selectedfrom the group consisting of hydrogen, halogen, —CH₂OR^(z), optionallysubstituted C₁₋₁₀ aliphatic, optionally substituted 6- to 14-memberedaromatic, optionally substituted 3- to 14-membered heterocyclic, andoptionally substituted 5- to 14-membered heteroaryl, and where any twoor more of R^(a), R^(b), R^(c), and R^(d) may be taken together to forman optionally substituted 3- to 12-membered ring, optionally containingone or more heteroatoms; L is a bond or a polyfunctional moiety; B is ahydrophilic oligomer having from about 4 to about 100 repeating units; nis an integer between 4 and 100; R^(z) is selected from the groupconsisting of R¹⁰, —C(O)R¹⁰, —SO₂R¹⁰, —Si(R¹⁰)₃, —C(O)N(R¹⁰)₂, or ahydroxyl protecting group; and R¹⁰ is an optionally substituted moietyselected from the group consisting of C₁₋₂₀ aliphatic; C₁₋₁₂heteroaliphatic; 6- to 14-membered aryl; and 5- to 14-memberedheteroaryl.
 23. The method of claim 22, wherein -B is selected from thegroup consisting of polyethers, polyolefin bearing hydrophilicfunctional groups, polypeptides, polysaccharides and polyamines.
 24. Themethod of claim 23, wherein -B is selected from the group consisting ofpolyoxymethylene, poly(ethylene oxide), poly(propylene oxide), polyvinylalcohol, poly(vinyl acetate), partially hydrolyzed poly(vinyl acetate),poly(acrylic acid), polyacrylamide, polyethyleneimine,poly(2-hydroxyethyl methacrylate), poly(N-vinylpyrrolidone),polypeptides, polysaccharides, polyepoxysuccinic acid, poly(methyl vinylether), poly(allylamine), poly(2-ethyl-2-oxazoline), and block, taperedor random copolymers of any two or more of the above.
 25. The method ofclaim 23, wherein -B is a polyether.